GS-35B homebrew amps

[Glenn NY4NC]

At my new QTH, I will have the luxury of having 220v in the shack for the first time in my ham career. Up till now, I've been using a linear amp running off the 110v line, with a single 3-500z to amplify my AM exciter, huffing and puffing along at 125w-150w carrier . It's time to up the power!... but..... gotta have 160 meters!.. I think 3-500Z's are great tubes, they're affordable, etc..

I'm considering an SB220 but it doesn't have 160m.. Any thoughts on modifying one for 160?... The drake L7 has 160 and uses a pair of 3-500's, more expensive...
My other option would be to homebrew something with a pair of Russian GS-35B triodes in grounded grid config.

The SB220 is a cheap and simple way out... even if I have to mod one for 160 but the GS-35B would make one hell of a slopbucket smashin AM linear big mawl CAW MAWN!!!

Thoughts?

[Pete, WA2CWA]

For starters, CQ Mag., Feb 1979, page 46
QST Mag, Jan. 1989, page 23
QST Mag. Dec. 1990, page 41
I think both QST articles were written by Measures.

Also a Google search on " SB-220 160 meters" turned up 4100 hits.

[W2VW]

SB220 works for quick. You will be chasing cooling issues when used on AM.
 Homebrewing any amp to cover all the way from 10 to 160 is not easy. A single GS-35B is definitely a good bang for the buck if homebrewing. Remember that you will need a chimney and a supply over 3,000 Volts.  If considering a pair of GS-35B then consider a single YC-156. Even better bang for the buck. No socket, uses a $40.00 chimney. You want 4,500 to 6 kV on one of these under load. Dynamic headroom is king when you want a clean signal.

[Glenn NY4NC]

Hi Dave;

I was just reading the Dick Measures article on modifying the SB220 for 160 meters

http://www.somis.org/add-160m.html


and just as you mentioned, the issues discussed are mostly related to maintaining wide frequency coverage. I absolutely do not need a KW on 10 meters, nor 15 for that matter. 160-20 is all I would ever want. I believe that makes the design challenge much easier, right?

You mentioned the YC-156, but I don't see this listed on the QRO-store site..  The more I think about it, the more I'm leaning towards building something. Sockets seem to be available for the GS-35, and a pair would make a killer amp!.. Probably the hardest component to find would be the power transformer. I believe a chimney can be made from PVC pipe, no? This guy sells a tube and socket for $200  http://www.nd2x.net/wb8wju-soc.html

Wher can I check out the YC-156? I assume that's a triode?

SB220 works for quick. You will be chasing cooling issues when used on AM.
 Homebrewing any amp to cover all the way from 10 to 160 is not easy. A single GS-35B is definitely a good bang for the buck if homebrewing. Remember that you will need a chimney and a supply over 3,000 Volts.  If considering a pair of GS-35B then consider a single YC-156. Even better bang for the buck. No socket, uses a $40.00 chimney. You want 4,500 to 6 kV on one of these under load. Dynamic headroom is king when you want a clean signal.

[Glenn NY4NC]

Check this site out if you haven't already....

http://www.nd2x.net/wb8wju-HF.html

Building a linear with a GS-35B for 160-20 should be a cakewalk!..

Anybody got a 3kv at 2 amp transformer they want to sell? 

[Glenn NY4NC]

Hey Dave;

I was gonna send you this link to W4ZT's GS-35 amp site... then I saw a link there to your GS-35 conversion article... 

His dual socket / teflon chimney arrangement looks pretty fine!

Ok' lets see, make that 3 KV at 5 amps!!! 

[W2VW]

Yup I'd say that Tony's chimney would be the way to go. PVC works but it sucks. Teflon is much better. You really don't need a socket. Just some brackets to fasten the grid ring down. I bought a whole socket for the chimney before running into W4ZT.
Do a Google on YC-156 then an ebay search on completed items and you will be on your way to an educated decision. Fill out the balance sheet and add up all the figures at the bottom. Yes, not requiring the higher bands makes things much easier.

[Glenn NY4NC]

That YC-156 is one scary looking tube Dave! 



I found some from one seller under completed items.. $179 that's cheap!!..
I'm gonna try and find the specs...filament requirements, etc..... One of the websites mentioned they ran it for 6 days a 40kw output and it didn't fail  Probably last forever at 1kw output continous duty.

Yup I'd say that Tony's chimney would be the way to go. PVC works but it sucks. Teflon is much better. You really don't need a socket. Just some brackets to fasten the grid ring down. I bought a whole socket for the chimney before running into W4ZT.
Do a Google on YC-156 then an ebay search on completed items and you will be on your way to an educated decision. Fill out the balance sheet and add up all the figures at the bottom. Yes, not requiring the higher bands makes things much easier.

[W2VW]

Heater is 15 V @ 15 A. Very modest. It needs to warm up for 6 minutes according to Eimac.

[Glenn NY4NC]

Yep, no doubt about it Dave, the YC-156 is the way to go...

Someone on one of the the corntest lists did some testing on a homebrew amp where an 8877 was replaced with a YC-156. Here's what he got...

14.2 Mhz.
50 watts drive
4300 Ep
.93 Ip
3999 watts input
1900 watts output
47.5% efficiency

He mentioned the efficiency went up to 58% when he increased the drive to 100w 

Can you say "really big mawl"?? 

Heater is 15 V @ 15 A. Very modest. It needs to warm up for 6 minutes according to Eimac.

[W2VW]

Interesting. I would never condone running more than 1500 Watts on the ham bands.
However, 1500 Watts with 6 db headroom would be significantly cleaner than a tapped out pair of 3-500Z's on a Voltage doubler supply. Gotta keep those signals clean.

[Glenn NY4NC]

I should have mentioned his testing was done into a Bird dummy load... 

I wouldn't condone it either,.... I might do it, but I would never condone it! 

Interesting. I would never condone running more than 1500 Watts on the ham bands.
However, 1500 Watts with 6 db headroom would be significantly cleaner than a tapped out pair of 3-500Z's on a Voltage doubler supply. Gotta keep those signals clean.

[Glenn NY4NC]

a most incredible, homebrew, YC-156, linear amp. ..
If you can find one to top this, I'd sure like to see it..

Take a look at this and prepare to drop yer jaw..

http://www.wv7u.com/yc156amp/yc156amp.html

Take at look at the "Test methods data and results"...

Very interesting... You would think the way to adjust output power on that bad boy would be to decrease plate voltage but that changes the IMD according to the author. Interesting stuff.