[ARC5] TVI Experience

[Geoff]

Nobody ever said it was but the T-150, or any 6M rig, was a case of front 
end overload along with harmonics from the 8.333 mc and up oscillators 
affecting higher channels. I had a T-150A and indoor HB 3 el at 3rd floor 
hilltop apartment in Warwick RI when I was in the USN. With 2 LPF's in 
series on the 150 and a HPF on the TV in another room the TVI was minimal.

Most all ham rigs built before 1952 or so were TVI monsters. That included 
the Johnson Viking I  I sold before joining the navy. After adding the TVI 
kit and a LPF it was pretty clean by itself but with the unshielded KW amp 
(made from BC-610 and other surplus) I was limited to 80-20M by parental 
edict!

An earlier post by someone gave misinformation about the 4D32. The truth is 
that tube was developed in the late 40's by Raytheon as a radar modulator 
for the USAF and they also released it for commercial use.
Production was restricted for the Korean War but soon after the war the 
radar was obsoleted.

Yet the tube was replaced maybe every 18 months (various reports give 12-24 
months) in inventory and old stock was destroyed minus the few that snuck 
out (hams are resourseful) . This went on into some year when the old ones 
werent removed and the new ones kept getting added. Around 10-12 years ago 
someone realized what was going on and cancelled the contract and somehow 
got the tubes released to surplus dealers. They never received a JAN number, 
they were all marked United States Air Force 4D32 and that was it. I bought 
several at $20 a pair with late 80's to mid 90's date codes as backups for 
the Viking I and 32V2 I use. These days prices are around $25 each and will 
keep those rigs plus the handful of HT-20's that were sold happy for a long 
time


----- Original Message ----- 
From: "Robert Eleazer" <releazer at earthlink.net>
To: <arc5 at mailman.qth.net>
Sent: Wednesday, October 17, 2012 7:57 AM
Subject: [ARC5] TVI Experience


> Remember, it wasn't just surplus gear that had TVI problems.
>
> Back in the mid-70's, soon after I got my license, a friend gave me a 
> Knight Kit T-150 transmitter that was U/S.  I had to replace the 6146B but 
> I dearly wanted to get on 6M AM, using it with my National NC-155.
>
> I was concerned about TVI and one evening saw my chance to run a test.  I 
> hooked the T-150 up to a length of wire strung around my apartment and 
> looked out the window where I could see a TV in an apartment next door, 
> tuned to the local channel 2.  I could see that no one was watching it at 
> the time.
>
> I keyed up the T-150.  For a second I thought the TV had exploded.
>
> It wasn't just surplus!
>
> Wayne
>
>
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