List members:
Bob (W4BD), George (N4GRN), Henry (W4HK), Mel (W4HJF), Rick (KC4HYM),
John (N4JML), Gordon (N4LR), Darryl (N4OME) and Tony (W4ZT)

Latest message on top. Share the wealth, find a stash, save the cash!

Date: Sun, 21 Nov 2004 01:15:36 -0500
From: w4zt
Subject: 2 tube socket lives

okay guys... here it is!

73, Tony

Date: Mon, 25 Oct 2004 08:42:15 -0400
From: Tony King W4ZT
Subject: Baking out tubes

Hi folks,

While most of us have not been very active working on our amps 
lately there have been a few interesting discussions about topics 
we need to think about.

One of these I have been following on the Amps reflector has been 
the discussion of "baking out tubes" or restoring old tubes to like 
new condition after many years of storage.  Besides the previous 
discussions we have had about "burn in" there is a school of thought 
that indicates that there is a need to apply a slowly increasing high 
voltage source between the anode and nearest element (grid) to the 
point that there is internal (or external) sparking.

I have posted a few links on my GS-35B discussion list that will 
give you the long and short of it I think.

What this does is make me wonder if building a hi-pot tester isn't 
a good idea and making sure that it will go to nearly 20 Kv and 
perhaps be able to do this kind of restoration work.


73, Tony W4ZT

Date: Fri, 09 Jul 2004 19:43:28 -0400
From: W4ZT
Subject: GS35B Amps - new link added

Hi Guys,

I've just received an email from Dominique, F1FRV, including 
links to logic, cathode control and metering boards that he's 
got there. I had a problem loading his page because it appears 
to require Internet Explorer and would not work with Mozilla 
or FireFox.

Here are the links:
Main page - (click on La technique)

(The following links WILL open with Mozilla)
Part 1, Logic Card -
Part 2, Cathode control and meters -
HV metering and OV trip -


Date: Tue, 22 Jun 2004 10:50:09 -0400
From: w4zt
Subject: HV power supply testing

After Field Day it'll be time to think about other things... 
maybe amps again.

I have in my mind to build a dummy load to test HV power 
supplies at the 3kv-4kv 1 amp level.

It'll be no easy chore to dissipate 3,000 watts at 3,000 volts 
without creating much smoke! I do have a plan and I'll share 
that with y'all later. I think I can put this thing together 
for under $50!


Date: Sat, 19 Jun 2004 16:03:33 -0400
From: w4zt
Subject: Fwd: [Amps] Eimac Tube Conditioning

Interesting reading... Tony

From: "craig vk3he" 
To: amps at contesting dot com
Date: Tue, 15 Jun 2004 22:56:21 +1000
Subject: [Amps] Eimac Tube Conditioning

 Tube conditioning was covered in a very long thread. Browsing through the
Eimac Web Page i noticed the following report AB21 Conditioning of Large
Radio Frequency Power Tubes. I cant seem to recall seeing it on their web
page before. It makes interesting reading. The comments regarding
conditioning the tube, and  then storing it in  the same position as final
operational position to avoid disturbing molecules makes interesting


Date: Sun, 30 May 2004 17:59:46 -0400
From: w4zt
Subject: single tube by wb8wju
I guess he posted this amp too... Tony

Date: Sun, 30 May 2004 17:56:26 -0400
From: w4zt
Subject: twin gs35b amp by wb8wju

Tom has all the parts in the box and working.  
Linked from his site here's the url to that project:


Date: Sat, 03 Apr 2004 20:01:39 -0500
From: w4z
Subject: New Member - N4GRN
Hi Guys, I'd like y'all to welcome a new member to the amp group. Meet George, N4GRN, another "local" living right here in Fairburn. Gordon, Rick and I had lunch with George at Oz Pizza today and found out that he's also interested in building an amp so we invited him to join us. George, don't hesitate to jump right in. Questions, suggestions, links we haven't found yet, anything you feel might help you or the group with the amp project are all fair game. List members include: Bob (w4bd), George (n4grn), Henry (w4hk), Mel (w4hjf), Rick (kc4hym), John (n4jml), Gordon (n4lr), Darryl (n4ome), and Tony (w4zt). Welcome aboard! 73, Tony W4ZT

Date: Thu, 1 Apr 2004 11:48:52 +0100
To: w4zt
From: G3SEK
Subject: Re: FW: RE: g3sek triode board

Hello Tony

Tom passed your message to me for reply. (Apologies for the delay 
that followed, which was all mine.)

>I'm convinced that Ian's board is the one to use but I have a 
>question or two.  I don't know if you can answer or if I need 
>to try to get ahold of him. I haven't seen an email for him.
>If you were going to have multiple RF decks, would it be advisable 
>to use only one triode board, say mounted in the power supply, 
>instead of using multiple boards, one for each RF deck?  Looks 
>like trying to use only one would introduce some unique problems 
>related to metering, bias and status indications.
>I've looked but it doesn't appear he has the instruction book on 
>his web site. It might help but haven't seen one yet.
>Tony W4ZT

The basic information is in the "interconnections 2" schematic 
which is a link from the Triode Board technical information page:

However, it *is* tricky to decide exactly what to do with 
multiple amplifiers.

I tend to think of it in terms of what you want to see from 
the operating position... and then you make the engineering 
meet those needs.

* The amplifier selection switch and the meters need to be 
right in front of you, where you can see them all the time... 
but that only requires a relatively small control box.

* The amplifiers need to be somewhere within arm's reach, but 
they don't need to be front-and-center.

* The HV supply needs to be out of the way, on the floor or 
in the bottom of a rack.

So that's three different locations. What I'd suggest is:

* A single Triode Board in the control box, with the Ig and 
Ia meters and the selection switch.

* In each amplifier, a separate heater transformer, blower 
and cathode connection - "cathode" being where the DC connection 
to the cathode comes out of the RF deck. The cathode connection 
in each amp should have a 10-22k resistor to ground, so that the 
tube is effectively cut-off when not in use (and a 90V spark gap 
or Varistor would be a useful backup).

You can then switch between amps from the control box by 
selecting the appropriate B-minus returns. The Triode Board 
takes control of the in-use amp, and the other tubes sit safely 
in the cut-off condition.

There may be some small interaction between amps, for example the 
grid current meter will not show exactly zero because of the small 
currents through the bias resistors in the unused amps.

All this assumes that all the amps will be OK with the same bias 
voltage, meter ranges, and trip levels for Ig and Ia... if not, 
don't worry - there are some work-arounds.

What you do with the B+ is your choice. You could either leave it 
connected to all the amps, or to switch it between amps. There are 
no strong reasons either way - except that it would be totally 
insane to open-up *any* of the amps when *any* part of this system 
is powered up. Even if you're not going to leave B+ on the unused 
amps, be absolutely paranoid about multiple ground bonding, with 
backups to your backup connections!
73 from Ian G3SEK

Date: Wed, 31 Mar 2004 23:40:13 -0500
From: w4zt
Subject: bleeder and meter multiplier board test

Well folks, John (N4JML), his son Michael, and I did a HOT 
test on the bleeder and meter multiplier board today and 
it works fine.  You can definitely feel the heat coming 
from it with 3600 volts applied but nothing is getting too 
hot individually. Had to parallel the two 1k resistors 
with ONE - 51 ohm resistor to bring the range of the 
10k pot in for a 50 ua meter movement.  All adjusted 
and works like a champ.

Next step....  put the juice on the 4-400s and see what happens!


Date: Wed, 10 Mar 2004 18:15:18 -0500
From: w4zt
Subject: Welcome to Mel, W4HJF

Welcome to Mel, W4HJF, joining us in the amp group.  
He'll be doing a desktop MLA2500 pretty much like 
WB8WJU has done.

Mel, take a look at and feel 
free to contribute links, ideas, items for discussion, 
parts discoveries or anything else you feel this group 
will find useful.

Hope you find this fun and enjoyable!


Date: Mon, 01 Mar 2004 23:14:01 -0500
From: w4zt
Subject: transformer wiring

Here's the basic wiring as a result of the tests we ran 
the other night. The actual voltages will have to be 
verified once I put full input voltage on it but this 
schematic will show you what we'll do and it plugs right 
into the circuit diagram of the g3sek triode control board. 

It is linked from the parts listing for the transformer:


Date: Mon, 01 Mar 2004 05:03:21 -0500
From: w4zt
Subject: HV control, blower, relays etc

Looking at the G3SEK triode control board and trying to sort 
out what we'll need external to it to make things play.

Here is the connection diagram showing the input AC control 
for the HV and Blower.  This covers the delay relay for 
inrush protection on the HV transformer, blower delay to 
keep it running even after shut down to insure cooling of 
the tube, and also shows us that we need another small transformer 
to provide control voltages for the relays.  The options are 
12 volt or 24 volt relays and since the vacuum relays for 
antenna switching are going to require the 24ish volts anyhow, 
I'd prefer to just use 24 volt relays throughout.  One thing 
this does not do is show the connection for a sail switch but 
that can easily be done:

This is the interconnections diagram that shows how it fits into 
the circuit providing the tube bias, metering and front 
panel LED indications:

There's a little better view of the metering etc on this diagram:

So, I'm adding the small 30 volt, 1 amp transformer to the parts 
list and the relays too.

I also moved the vacuum variable info off to its own page.


From: n4lr
Subject: Re: Improving Relay Operate Time - Kilovac
Date: Sun, 29 Feb 2004 13:20:06 -0500

I dont know but I have seen a message or two on this... 
I see if I can find them again.. Maybe this is a good 
question for the amp reflector..

----- Original Message ----- 
From: w4zt 
To: n4lr 
Sent: Sunday, February 29, 2004 1:02 PM
Subject: Re: Improving Relay Operate Time - Kilovac

yes that is.

Now, I have to ask you this... at what cw speed is 
this going to become a factor?

What is the dit time at 20 wpm?  35 wpm?  
Can you go faster?

Then we have to consider a 48 volt supply in the 
amp and switching it with the key lead.  How are we 
going to switch it?  If it has to be switched with 
ANOTHER relay, how fast is IT going to switch?  
I'm just trying to figure out if we really need an HC-1 to be faster.


At 12:16 PM 2/29/2004, you wrote:

Date: Sun, 29 Feb 2004 07:47:41 -0500
From: w4zt
Subject: chimney alternative

Here's an interesting alternative:

See the 5th picture down and click on it.
Text next to the picture says:

"View of the air flow "chimney" of the GS-35b. This tube 
requires at least 90 cubic feet per minute (~150 cubic meters 
per hour) of air flow to keep tube temperatures within spec's. 
The "chimney" is a 100mm PVC conduit junction. It is bolted 
to the chassis by 4 "L" brackets. On the bottom of the conduit 
is a gasket of cork material to get a good air seal. The air 
entry port of the system accepts a 50mm PVC conduit fed by a blower".


Date: Sun, 29 Feb 2004 07:36:15 -0500
From: w4zt
Subject: GS-35B tube cost compared

More from our discussions yesterday...

GS-35B from Tom: $119.95 plus shipping:

GS-35B from *RUSSIA*:
Single tube:

Buy it now:                $73.00
Shipping and handling:     $28.00
Shipping insurance:         $7.00
Total delivered:          $108.00

Two tubes:

Two tubes:                $135.00  (or $144 buy it now)
Shipping and handling:     $48.00
Shipping insurance:         $7.00
Total delivered:          $180.00 ($90 per tube)

It's interesting, this tube can be purchased WITHOUT the 
cooling fins, a good way to have a spare. $59.99 + Shipping 
and handling: (first item) US $17.00,  Cost per additional 
item:  $12.00  + Shipping insurance: $4.00 for a total 
of $80.99 for the first spare then $75.99 for each additional one:

A lot of TEN tubes:

Buy it now:             $595.00
Shipping and handling:  $195.00
Shipping insurance:      $45.00
Total for ten tubes:    $835.00  ($83.50 per tube)


Date: Sun, 29 Feb 2004 06:58:21 -0500
From: w4zt
Subject: GS-35B socket

Going back to our conversations yesterday...

The socket/chimney combination for this monster is available 
directly from WB8WJU, who appears to be the maker of the things, 
for $20 less than other places; $70 delivered including schematics:

Now, combine that with the less expensive tubes if you will, 
and see how it looks.


Date: Sat, 28 Feb 2004 21:37:50 -0500
From: w4zt
Subject: Iron

Take a look at this:

Based on that, I'd say 50 lbs yields 1.3 KW CCS and off the 
scale for ICAS, probably upwards of 3 or more.


Date: Wed, 25 Feb 2004 06:52:27 -0500
From: w4zt
Subject: Power Supply Filter Caps

Gordon and I were looking at a cap on Ebay but found 
that a nice one is at

It's 32 uf at 4500 VDC oil filled which should just 
about fill the bill and actually gives you as much 
capacitance as a stack of 10, 320 uf, 450 volt 
electrolytics without all the parallel balancing resistors.


Date: Wed, 25 Feb 2004 06:31:10 -0500
From: Tony King w4z
Subject: Questions for discussion

I've added a link on the amp page,, 
to questions we might want to discuss. It's a short list 
but certainly should get longer. Just some things that I 
came across and thought I would share.  Please feel free 
to send me others you think that would be good to add to 
that list. I've tried to provide a link to some answers 
so it's not just unanswered questions.


Date: Wed, 25 Feb 2004 06:25:16 -0500
From: w4zt
Subject: Roller Inductors on Ebay

Just found an item on Ebay that was JUST posted within 
hours ago for a 7 day listing, 6 days 17 hours remain.  
It's a complete old Heathkit antenna tuner with roller 
inductor and large air variable caps. For the price, it 
might appeal to someone.  Buy it now price is $125 with 
a reserve which is probably near that same price:

There are three others that are very interesting as well.

The first is a large open roller inductor that has been 
repaired.  One of the ceramic end pieces has been replaced 
with plexiglass but otherwise the unit looks very nice.  
There are 3+ days remaining, no "buy it now", and the 
current price is $30 with one bid:

The second is a smaller roller inductor with turns counting 
dial.  It has the single roller contact with 35 turns on a 
ceramic form about 2 inches in diameter:

The third is a group of 3 components to build a tuner.  
There is a very nice roller inductor with tapered turns 
on one end (this is a nice one), a large split stator 
tuning cap and a broadcast style loading cap.  It's now in 
the $20 range but should move up some over the remaining 4+ days:

Share the wealth, find a stash, save the cash!

Date: Sat, 21 Feb 2004 01:30:49 -0500
From: w4zt
Subject: Parts list - vacuum variable chart added

I just added a chart which is the result of a query 
on the Jennings site.

It shows the capacitors in their current product 
line that have a maximum capacitance between 250 and 
500 pf.  I then highlighted the ones that fit into our 
window of need so you can see what they are.

These don't carry the old "UCS" numbers that we're used 
to seeing and I haven't found a cross ref on that yet but 
I did find another site which has some listed so I put 
that link below the chart.


From: kc4hym
Subject: RE: amp links page redesign
Date: Fri, 20 Feb 2004 20:44:29 -0500

Good stuff for amp beginners like me

----- Original Message ----- 
From: w4zt
Sent: 2/20/04 9:14:41 AM 
Subject: amp links page redesign

I redesigned the links to include thumbnails of the 
pages they refer to:
Also the mail archive appears to be okay. I strip out 
headers and addresses:

From: n4lr
Subject: 144_new_amp
Date: Thu, 19 Feb 2004 23:54:24 -0500

nice construction pictures..
P.S. Tony... He's using the wd7s graph display... (link added, tk)

Date: Thu, 19 Feb 2004 23:50:04 -0500
From: w4zt
Subject: roller inductor and loading cap

the coil and the loading cap look good

From: n4lr
Subject: {Collins} Re Millen Products
Date: Thu, 19 Feb 2004 23:51:48 -0500

i see a lot of messages on the internet about Millen HV 
connectors not being the best choice.. 

Date: Thu, 19 Feb 2004 16:03:25 -0500
From: w4zt
Subject: Re: new link ?? - ADDED

That's a nice page!  I've added the link:

At 03:48 PM 2/19/2004, n4lr wrote:

This is another 8877 link but at the moment the power supply info is what
interests me..

Look at the how do I get started section..

Gordon N4LR.

From: n4lr
Subject: very rough cost estimate
Date: Thu, 19 Feb 2004 16:59:17 -0500

Transformer	1 ea	350	350	
25 5000 cap	1 ea	100	100	
330ufd 450 vdc	10 ea	2.75	0	
k2aw 14kv rec	4 ea	15	60	
51k 15w bleeder	10	0.54	5.4	
50k 7w bleeder	10	1.5	17.5	
	subtotal	532.9		
control board			135	
gs35b/socket			189	
	tub/control	324		
plate tune cap	1	65	65	
cathode tune cap	1	85	85	
blower	1	50	50	
plate choke	1	24.95	25	
cathode choke	1	17.95	18	

From: n4lr
Subject: new link ??
Date: Thu, 19 Feb 2004 15:48:25 -0500

This is another 8877 link but at the moment the power supply info is what
interests me..

Look at the how do I get started section.. 

Gordon N4LR. 

Date: Thu, 19 Feb 2004 15:47:26 -0500
From: w4zt
Subject: Re: plate transformer and modules

CCS = Continuous Commercial Service - Key down, 24/7

ICAS = Intermittent Commercial & Amateur Service - 
Not running RTTY? it's ok

Sure CCS would be better. It means there's more 
iron in the core and it dissipates the heat. The windings 
are probably the same size wire for the current you're going to draw.

And pulling in your other questions:
"Which ones do we need. It looks like I've seen the 14kv used most of the
time.. They go down to 6kv which are $5 vs $15   x 4    ???"

The diodes (block or string) in a bridge configuration are 
going to see the full peak AC voltage from the transformer 
secondary across each leg of the bridge. In your example below, 
the peak AC voltage is 3535 and it is wise to double that for 
your diode PIV (peak inverse voltage) rating.  Since the K2AW 
blocks are built from 1 kv diodes the 6kv model falls short 
of the 7070 volts that would be double your example.  
Would it work?  Probably. Would I use the larger one? Yes.

"Looks like a new Peter Dahl transformer will be about $350..
I am still not clear on volts / amps...  "IF" our target was 
3500 v then  Secondary 2500v x 1.414 = 3535 ???? at 1 amp ??? 
Sorry but I'm somewhat

Right on! That would be close enough for me or anyone else.  
This 1.414 stuff really does work and has for the over 40 years 
I've messed with it. I agree that $350 is a lot of cash for a 
transformer.  That's why shopping around is a good thing. BUT, 
it is ALWAYS an option if you can't or don't find what you want 
or if you find something and want to change it later.  I'd like 
to see the transformers that the guy around here makes too.  
For me, it isn't important that it carry the Dahl name but that 
it doesn't leak smoke.


At 03:27 PM 2/19/2004, n4lr wrote:
If you look at the Peter Dahl site . They have a series starting with the
letters ARRL.

ARRL-00X .... They are all $350 and 46 pounds. They have varying voltage
choices at 1.5 amps ICAS... I see some transformers rated at CCS not ICAS.
From looking at the prices I think the CCS is higher duty cycle..

for example: this one looks good but I dont plan to spend $350 on a
transformer.. At least I hope not.

1900-2100-2600-2800 VAC AT 1.5 ICAS


Date: Thu, 19 Feb 2004 15:30:11 -0500
From: w4zt
Subject: Re: Plate Transformer

hmmmm... at that price does it wash the dishes too?

At 03:16 PM 2/19/2004, n4lr wrote:
Here is one that will work !!!

5200/4800/3900/2300V @ 3A CS PLATE XFMR WITH +10,0,-10,208,240V PRI CORE)
A-0550/ C-CORE STYLE #) 10 HIPERSIL C-CORE PR) +10,0,-10,208,240 VAC 60 HZ 1
PH S1) 0-2300-3900-4800-5200 VAC @ 3.0A CCS DM) HT = 15.688 WT = 15.950 DT =
10.750 MD = 6.750 MW = 10.000 PRICE) $1,475.00 Plus S&H FOB El Paso, TX

Date: Thu, 19 Feb 2004 15:02:10 -0500
From: w4zt
Subject: Re: K2AW Hi-Voltage Modules

That is an interesting testimonial FOR the K2AW blocks.  
He matches all the diodes before potting them so they are 
as balanced as they can be. As was said in it and the message 
that followed it, if you are going to take the time to build 
up your string of diodes properly with balancing resistors 
and capacitors (do we have the facilities to pick balanced 
diodes? no), then you are probably going to put more time 
and money into your diode stack.

That said, it is likely that I have a bag of diodes and 
caps and resistors all sitting waiting for me to build my own.  
They are what I have because I collected them when there was 
not a better option. Bob may already have the same thing.  
BUT, if I find I have to reconsider it, the K2AW modules 
will be at the top of the list.

The power supply is a simple device yet so important 
that if we skimp, it can go up in a shower of sparks that'll 
make you think I was welding in your shack. Three to five 
thousand volts at over an amp is VERY unforgiving.


At 10:33 AM 2/19/2004, n4lr wrote:
Here is a message I found on the internet for the group. 
I am investigating a cheaper alternative to the k2aw which at $15 times 
4 plus shipping for the power supply.

This didn't cut and paste too well. It's easier to read at the below link..

Gordon N4LR

Before shooting of our mouths about a very nice person and his very nice
products, why not take a moment or two to get the facts? Deja-vous, eh Rich?

1. K2AW Modules are made by hand by K2AW, with TLC!

2. Each module has a
string of General Instrument 1N5408 diodes, personally matched by Frank
before potting in "environmentally correct" epoxy. The 6kv module has 6
1N5408's, the 14kv module has 14 1N5408's etc.

3. Although the diodes are
rated at 3 amps, Frank derates the module to 1 amp to make them "idiot
proof" as they are used all over the world by many services.

4. There are
over 20,000 modules in use in over 50 countries.

5. As I stated earlier, I
have abused his products for 15 years with ZERO FAILURES. IMO, the use of
strings of diodes and strings of electrolytic caps with strings of
equalizing resistors feeding strings of vacuum tubes is something only for
the amateur, C.B., and "freebander" markets where cost is the number one
factor. This all works fine and saves a few bucks initially, but long-term
reliability suffers, especially in power supplies delivering 5000 volts plus
at several amps. One only has to look at RF equipment designed for
industrial/military use vs the equipment for the amateur market to confirm
this point. When one is pontificating about the use of components in a power
supply, why paint with such a broad brush? Is this power supply going to be
used for a tube with handles, or one of the popular "table-top toy" circuits
popular today?

There are thousands reading this reflector. I call them the
"silent majority." They never post an article. Before one begins an
assassination of a product or an individual, one should get the facts to
avoid ramification. Those who do not bother to do this leave me with the
impression that they may have a personal axe to grind, for whatever reason.
There was absolutely no excuse for spreading the rumor on a technical forum
that K2AW sells microwave oven diodes.

Some day it might be your turn "in the barrel"...have fun!

(((73))) Phil, K5PC

Date: Wed, 18 Feb 2004 10:23:37 -0500
From: w4zt
Subject: power supply filter caps

And Gordon asked me: "how much is enough" in terms of 
capacitance on the power supply.

For a full wave rectifier, either bridge or center 
tapped, you'll probably want 25 uf or more.  That isn't the 
case with a voltage doubler but we're not talking about one 
of those.  Typically the old saying "more is better" applies.  
The cap I plan on using in my HV power supply made Gordon's 
eyes bug out when he saw it... it's 130 uf at 5,000 volts, 
oil filled.

That brings us to the question of oil filled or electrolytic?  
Electrolytics are light weight, sometimes smaller, and MAYBE 
cheaper in the short term.  The building of the capacitor bank 
using electrolytics makes you consider the series string of low 
voltage electrolytic capacitors, typically 450 volt units to 
obtain the high voltage necessary.  If for instance you were 
targeting a max voltage of 4500 volts, that would be ten 450 
volt units in series.  That's all well and good but it also 
divides the capacitance by ten.  One typical supply filter bank 
we looked at had ten 220 uf 450 v electrolytics in it so the 
capacitance was 22 uf for the supply. The electrolytics also require 
balancing resistors across the caps to maintain equal division 
of voltage across them.  Now that may not be a bad thing because 
you'll need a bleeder of some sort on the oil filled supply but 
not like that required for the electrolytics.

Pricing may be near the same these days.  We were looking at 
a NEW OLD STOCK Henry capacitor on Ebay and they were wanting 
$99 by it now for 25 uf.  If you were paying 8 to ten bucks a 
piece for electrolytics then the price would be nearly the same.  
The oil filled cap will last much longer, probably a life time. 
That's a better deal in my book.

So, bottom line, it's your choice.  My personal preference is 
the oil filled cap and that's what I'll use.  If you were going 
to spend the big bucks and try to make it small then electrolytics 
and a Dahl transformer would probably burn a sizable hole in your pocket!


Date: Tue, 17 Feb 2004 18:19:50 -0500
From: w4zt
Subject: Loading caps

Here's a view of an acceptable loading cap:

This one is only 800 pf so slightly small:


Date: Tue, 17 Feb 2004 18:19:02 -0500
From: w4zt
Subject: Plate tuning cap - was i'm bidding...

There are others available as well.  That one is GREAT 
looking Gordon!!!

Here is another, not as desirable but still in the ball park:

This one is larger and one would have to work on the attachment 
hardware, which is no trivial chore:

Here's a Russian one (I wouldn't send MY money to Russia!):


At 06:05 PM 2/17/2004, n4lr wrote:
I am bidding on a plate tunig cap. I expect this to go to $100 or more..

Item number: 3079059781
Jennings UCS-300-15S Vacuum Capacitor 15KV

Date: Tue, 17 Feb 2004 17:25:30 -0500
From: w4zt
Subject: parts list update

I just updated the parts list. My apologies for the 
stupid listing of a plate voltage meter of 1.5 KV, 
it's now listed as 5 KV.

I also noted:

The need for two vacuum relays, one to switch input, 
one to switch output (they are tied together in receive).

The minimum capacitance limitation for the plate tuning 
(about 15 pf) and max voltage for same (>7500v).

This is an on going process.  Other changes will come and 
I'll let you know if I make a change on the web page.


Date: Tue, 17 Feb 2004 17:05:00 -0500
From: w4zt
Subject: amp control board

Well it seems that G3WOS is thoroughly taken with the control 
board by G3SEK.  This is the control board that Tom ( 
sells and recommends.

Gordon, I think you did a pretty good comparison of the two, 
perhaps you could just list the features side by side 
(without a spread sheet?) and we could see how it stacks up.  
I'm particularly interested in the built in metering capabilities 
and variable bias.

Nothing says we have to use the same one, but it'd be nice to know 
all the pros and cons of the two side by side. I'd really rather 
build one of the two as a kit than build the thing from scratch.


From: w4zt
Date: Tue, 17 Feb 2004 16:34:38 -0500
Subject: RE: ebay

well it takes two... you have to switch the output and the 
input so a second one is in order.

Allen Bond is OUT of them right now and is carrying a 
waiting list.  He expects more but doesn't know if there will 
be enough to fill or go over the list.  If we want some from 
him, we should put ourselves on the list for some number.

He will be at the Hamfest in Dalton

ALSO... he has the turns counter dials.  Two types, the 
Henry Radio type.. flat looking, for about $25 and a refurbed 
nice looking EF Johnson for $35.  He will not be bringing the 
EFJ's to the hamfest unless we specifically request them.  
They are my preference I think.  You only need one if you use 
the roller inductor.  Another if you were to use a vacuum variable.


At 03:21 PM 2/17/2004, Rick wrote:
Jennings RJ1A vacuum relay, I already got his other one

From: kc4hym
Subject: RE: ebay
Date: Tue, 17 Feb 2004 15:21:47 -0500

Jennings RJ1A vacuum relay, I already got his other one

----- Original Message ----- 
From: n4lr
Sent: 2/17/04 3:10:39 PM 
Subject: RE: ebay

hey i need a lot of stuff...
-----Original Message-----
From: w4zt
Sent: Tuesday, February 17, 2004 2:53 PM
Subject: Re: ebay
you're watching too much!  LOL!!!!
refine the searches and don't use as many
At 02:47 PM 2/17/2004, you wrote:
>I keep exceeding the limit on the number of items to 
watch... never done
>that before..

From: n4lr
Subject: RE: GS-35B amp links and parts page
Date: Fri, 13 Feb 2004 09:59:22 -0500

so is the key to find the transformer first.. we already know the

-----Original Message-----
From: w4zt
Sent: Friday, February 13, 2004 9:44 AM
Subject: RE: GS-35B amp links and parts page

This will depend on your choice of transformer.

At 09:38 AM 2/13/2004, n4lr wrote:
>k2aw hi-voltage modules...
>HV 14-1   14KV-1A 250A SURGE $15.00
>2 EA ?????? 

From: n4lr
Subject: Cable-Wire - EBM CENTRIFUGAL BLOWER G2E120 SERIES - 1062
Date: Sun, 15 Feb 2004 21:38:49 -0500

From: n4lr
Subject: K7EM - Henry Radio 5K Classic Amplifier Home
Date: Sun, 15 Feb 2004 20:29:52 -0500

Well i was going to inquire to the group about the dayton 
blowers but decided to do a google search , here is the first 
thing i found... doesnt sound good.. havent read the upgrade 
yet but maybe interesting..
we should create a group to email to.. maybe a yahoo group 
with only us as members.. or maybe sam could create one where sfares is..

Date: Sun, 15 Feb 2004 22:10:29 -0500
From: w4zt
Subject: Re: test

Yes, for the amp group only, if you received this, you can 
reply to it and it will go to all  of us. Or if you want to 
send a new email just send to amp at w4zt dot com with your links, 
ideas, finds, etc.

Set it up with simple email forwarding so we didn't have 
to keep remembering who to send it to!

Share the wealth, find a stash, save the cash!


PS... Gordon, share that blower  info with the group.

At 09:45 PM 2/15/2004, you wrote:
Wow !!!.. We now have our own mail group..  Just email xxxxxxx 
to talk to the whole group..

Date: Mon, 16 Feb 2004 09:50:52 -0500
From: w4zt
Subject: measuring variable capacitors

Biggest problem with surplus variable caps is figuring out the range.  
It's worse at  hamfests. I just discovered one of those Rainbow Kits 
I purchased eons ago that'll allow you to roughly measure caps down 
to 2pf with a DVM.  I think I'll slap that together and see if I can't 
get it to work ok in the range of 10 pf to 1000  or 2000 pf and take 
it along.  It's supposed to check higher values than that easily up 
to about 2 uf. My DVM will do caps but not that low without the add on.

I see they also have a little inductance tester, which I don't have, 
that would be nice for coils. quicker than a grid dip meter and cap 
and it's portable. Anybody have one?


From: n4lr
Subject: RE: Roller inductors for plate tank coil
Date: Mon, 16 Feb 2004 09:43:26 -0500

Hi John,
I have been doing a lot of research but haven't bid on anything yet.. 
Still trying to get the big picture as far as cost is concerned.. 
This project is a stretch for my knowledge.. What to buy is a big 
learning curve for me.. I dont know a 1 uh roller inductor from a 
million uh roller inductor.. but after scanning the internet way past 
my bedtime last night , I now know..
229-201 is 10 uh
229-202 is 18 uh
229,203 is 28 uh
Johnson is the standard.. They are now called Cardwell. So if you 
search ebay look for both..
Talking to tony looks like we can work with the 202 but 203 would 
be better. matter of $$$ vs convenience.
Gordon N4LR

Date: Mon, 16 Feb 2004 09:34:55 -0500
From: w4zt
Subject: Re: Roller inductors for plate tank coil

I think you're right. Besides, Bob and I have discussed the need 
to parallel some capacitance across the plate tuning for 160 meters. 
Reason, unless you use a vacuum variable, the physical size will 
make the minimum capacitance so large that it can't tune ten meters. 
So, if you're going to switch in a doorknob cap for the plate, opening 
a shorting contact across the extra coil on the cool end of the tank 
wouldn't be such a hastle. I think that coil would work fine with the 
add on. Bob, chime in here if you check your mail.

John, I agree on the bidding war.  Bob and I have already got our roller 
inductor.  I'll be happy to place the bid for something if y'all need that.  
We definitely shouldn't bid against each other ;)

I expect we'll end up with extra pieces as we shop and "find something better" 
and that's unavoidable. Just have to move them later.

Darryl, hope it's warm there.  I have to get out and replace my 
alternator belt today that keeps slipping. It's only going to be 45 they say.


At 09:24 AM 2/16/2004, n4ome wrote:
That roller inductor looks very similar to the one in the Johnson Viking 
Thunderbolt Amp that doesn't work 160m.  Back a few years ago I modified 
that amp to work 160m and had to add a coil (about as large as the roller) 
in series with the roller operated with a relay to switch it in and out.  
If you go that route then you might could operate a relay in conjunction 
with the band switch.


From: n4ome
Subject: Re: Roller inductors for plate tank coil
Date: Mon, 16 Feb 2004 14:24:02 +0000

That roller inductor looks very similar to the one in the 
Johnson Viking Thunderbolt Amp that doesn't work 160m.  
Back a few years ago I modified that amp to work 160m and had 
to add a coil (about as large as the roller) in series with the 
roller operated with a relay to switch it in and out.  If you 
go that route then you might could operate a relay in conjunction 
with the band switch.


Johnson Roller Inductor 229-202

Last one on Ebay went for $64.52 

These are $150 at

This coil MIGHT reach 160 without  additional inductance but I wouldn't count 
on it. We know you'd have to add a strap for ten meters so a little bit added 
for 160 is no big deal.


Date: Mon, 16 Feb 2004 00:09:16 -0500
From: Tony
Subject: Roller inductors for plate tank coil

Johnson Roller Inductor 229-202

Last one on Ebay went for $64.52 

These are $150 at

This coil MIGHT reach 160 without  additional inductance but I wouldn't count 
on it. We know you'd have to add a strap for ten meters so a little bit added 
for 160 is no big deal.


From: wb8wju
To: Tony
Subject: Re: GS-35B amp, referred by Tom Hix
Date: Thu, 12 Feb 2004 07:48:57 -0500

  Hello Tony,
  Here are the numbers using 3600VDC@1.2A as a source
  Input resistance 1786
  FREQ.      C1     Ind.     C2
  1.8       477    16.9     2585
  3.9       196     7.8     1193
  7.2        85     4.2      646
  14.3       21     2.1      325
  18.1       20     1.3      345
  21.3       20    0.99      358
  28.5       20    0.56      370

Date: Wed, 11 Feb 2004 23:00:55 -0500
To: wb8wju
From: Tony
Subject: Re: GS-35B amp, referred by Tom Hix

Hi Tom,

Thanks for the speedy reply.

>At 07:36 PM 2/11/2004, wb8wju wrote:
>Hello Tony,
>Glad to help I have tried  both ways with and without the parasitic choke
>only a small difference.(DON'T need it.)

That's good news!

>If you want  160 meters you will need a total or 30uH on your roller for a
>single 1/2 that for a pair.

okay... one tube, 30uh will be fine.  I'll have to measure mine and if 
it isn't enough, a small add on can be done.  I think it will work. It's 
one of the old long rectangular wire types. Solid and in good condition.

>How much DC Voltage are you going to have?Let Me know in your next email
>and i will run a program PULL DOWN VOLTAGE. and send it along with my pick
>for a schematic.

I'm not wanting to blow the lid off this thing but I'm open to suggestion 
(that means I'm easy.) I figure 3000 to 3500 though up or down a little 
doesn't really bother me. The big variac will keep the poll pig in check ;)

Thanks so much for your suggestions.  I've read all these links and been on 
every page on your web site I think.  You've spent a lot of time doing this 
sort of thing.  I spent ages collecting parts for a 4-1000 and now it just 
doesn't have the appeal.  Too much trouble getting ten meters and lots of 
other stuff.  This seems so clean and I'll enjoy it more even though I wont 
be able to see that warm glow!  (of course I could put the 4x1 over in the 
corner of the box and light the filament just to keep me warm) ;-)

Tony W4ZT

To: w4bd,w4hk, n4jml, n4lr, n4ome
Date: Wed, 11 Feb 2004 11:42:51 -0500
From: Tony
Subject: GS-35B amp links and parts page

OK guys, here are the links and the beginnings of a parts list. Did you 
know all of you were interested in this?

Send only GOOD links and I'll post them to share... after all, we do need 
one good place to go for them when we get to talking about it.

It is also linked from my  web page at

Remember, no layout or construction until all the RF deck parts are in hand.

Share the wealth, find a stash, save the cash!