[AMRadio] In Defence of Old Buzzard Transmissions

Floyd Hollister fhh11 at columbia.edu
Mon Oct 12 23:53:39 EDT 2015


Thanks for the info on the coax relays 

I am about to build a sequencer for my Gates BC500G which I hope to get on
the air this winter.  What model Gates are you using?
I am looking for a replacement bias transformer for my BC500G.  Mine burned
out and is internally shorted. It is Gates P/N 472-0453-000.  I have worked
out a scheme to make the rig function using two back to back control
transformers, but I would like to keep it as it was manufactured, hence my
need for the transformer.  Do you have any idea where to look for one?  I've
tried eHam.net and eBay with no suc.

When you switch from R to T do you activate the Oscillator, RF and AF
drivers at the same time as you apply the HV to the 833 Modulators and RF
finals or just a few milliseconds earlier? 

I am really enjoying bringing this rig back to life.

Floyd, K2DUV 

-----Original Message-----
From: AMRadio [mailto:amradio-bounces at mailman.qth.net] On Behalf Of Donald
Sent: Monday, October 12, 2015 5:38 PM
To: 'Rob Atkinson'
Cc: 'Discussion of AM Radio in the Amateur Service'
Subject: Re: [AMRadio] In Defence of Old Buzzard Transmissions

> I spent an entire day a few years ago experimenting with relays to 
> come up with a method that would best isolate the rx on transmit and
protect the input coil.   The way I do it now is almost too good
because I can't hear the 122 VFO for spotting on the CW rig.  On the
3-400 rig I spot with both the vfo and driver
>Rob K5UJ

I picked up a shoe box full of little coaxial relays at Dayton one year.
They work exactly like miniature Dow Keys, but have 24 vdc coils and use BNC
connectors. I use them to select which transmitter the VFO feeds to, and
with the receiver, to select what feeds into the antenna terminal.  On
receive it selects whatever receiving antenna I have selected with a rotary
switch.  On transmit, it completely disconnects the antenna input terminal
from anything else and, to boot, grounds it.  I can hear my VFO well enough
for spotting, but sometimes I have to switch to a different receiving
antenna to get enough signal.  I have a  separate spotting switch, so I
don't have to  switch to transmit to hear the VFO.

Lately I have been using my 3885 kc crystal for 75 while keeping the VFO
connected to the Gates for 160.


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