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 on: Today at 01:56:38 AM 
Started by pe1mph - Last post by pe1mph
Hello AM Lovers,
Last night (early in the morning) I were out bed: toilet and drink something.
Later I listen to sw and mw, starting +/- 04.45 hour Summertime (02.45 hour GMT Time).

On my own radio! Wink
On 3873 khz very weak some stations...
On 40 meters I heard some stations talking!

- 7287 khz, KB?Huh (3 or 4 stations, but I could not copy calls/names)
- 7295 khz, KB3??? (Glen?)

The freq. 7287 were not free / clean by me and close by a BC station.
The freq. 7295 were good, free and clean by me!

I made a short recording from the station on 7295 khz, perhaps....
He heard himself..... hi, hi...

A pity we (in Europe) may not use that part of 40 meters, but.... hi, hi...
Perhaps I try it in a morning, to get a short qso on that part of 40 meters in AM.
Because during the night I have less band NOISE on sw.

So this morning between 7290 - 7300 were free /  clean by me.
I used my Kenwood R-5000, standing in our living room.
Antenna 2x +/- 33 meters long, connect to home-made antenna tuner.


Henk / pe1mph
Dokkum /  The Netherlands

 on: Yesterday at 12:05:05 PM 
Started by W3GMS - Last post by W3GMS
Will not ship, but can bring to NEAR-Fest.  Price $800.

 on: Yesterday at 09:25:03 AM 
Started by ua3ral - Last post by Tom W2ILA
He wasn’t the first cosmonaut.
He was the first cosmonaut to land alive.

 on: April 12, 2024, 08:35:51 PM 
Started by WU2D - Last post by Pete, WA2CWA
There were 4 versions of the Gonset GSB-201 in its life cycle.
There was the GSB-201, GSB-201 Mark II, GSB-201 Mark III, GSB-201 Mark IV.
Gonset only manufactured the first model GSB-201. The 201's with suffixes were manufactured by Aerotron.
The GSB-201 and 201 Mark II used four 811A's.
The GSB-201 Mark III and IV used four 572B's.

With each passing model, there were more features and enhancements.

Good info to have available for idle hit-chat at your next amateur radio cocktail party.

 on: April 12, 2024, 06:46:07 PM 
Started by WU2D - Last post by WD5JKO

Hi all,

  I too have a GSB-201. Got it about 20 years ago from a Dale, KW1i.

My issues with the amp were many, but two big issues:

1.) one side of the tube filaments is grounded. This creates 60hz cathode modulation. The fix is to make a artificial centertap with resistors, or use a LV winding of another filament transformer that has a CT.

2.) The input SWR was < 2:1 on bands 40-10m, but 8:1 on 80m. Something was wrong with the filament choke. After replacing the choke with one designed for 160-10m, the 80m SWR issue was fixed. I lost the neutralization winding, but using a remote tuner on the input (about 12" RG-8 to tuner), working 15, and 10m is fine. There is a slight offset between plate current dip, and maximum RF output.

I made some changes to the bias circuitry. I kept the -100v cutoff bias during idle, and added two bias circuits selected by a added switch. I use a string of 1N4005's to get -4.5v for SSB (class B), and a 12V 50W zener for AM (class BC, biased at cutoff). The diodes complete the path from filament CT to ground.

Running 811A's with 12v bias at 1500v B+ is pretty much right at cutoff. That lowers the gain about 3-4 DB, and by boosting the drive, the modulation positive peaks climb up there nicely. The output modulation is slightly greater than the input modulation. I can run 180w carrier output with headroom for > 120% positive peaks. Efficiency when run this way is higher, high 30's%. Just remember to switch bias to -4.5v for SSB!

The GSB-201 is the most reliable linear I have ever owned.


 on: April 12, 2024, 11:26:34 AM 
Started by WU2D - Last post by N4ZAW
I took the schematic and greatly reduced the resolution. Hopefully it uploads. The 1.5M file would not go.

I know this is an old thread, but thank you for it! VERY COOL! I've had a GSB-201 under my bench for almost 30 years, threatening to bring it into the 21st century... Well, I'm retired now, and have it ON that bench now, completely gutted.
I just found this via a link while searching for bias schemes for mine. I've already gotten a lot of inspiration from you and this thread.
The "before" pic;

 on: April 12, 2024, 10:16:10 AM 
Started by W7TFO - Last post by W7TFO
Thanks for those links, Pete.


 on: April 12, 2024, 09:58:22 AM 
Started by w4ax - Last post by W3SLK
Ken, W2DTC built 2 3CX3000F7s, (the F designation doesn't require a socket). He did a helluva job on them too.

 on: April 12, 2024, 08:33:23 AM 
Started by ua3ral - Last post by RolandSWL
Vee shore Dat Dat is lady?  Jess?



 on: April 12, 2024, 06:17:14 AM 
Started by ua3ral - Last post by KD6VXI
Vee shore Dat Dat is lady?  Jess?


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