[Central-Electronics] Vintage Ham Shack for Sale - Includes 100V

[Jim candela]

Lyman,

    Congratulations on the 100V project. If the thing doesn't sell, consider
a "cloud burner" low dipole on 160-80-40 meters. That should give you enough
high angle elevation to get over those hills, and give you a good short skip
distance. I've heard that sometimes you can make a 2 element beam pointing
straight up for a little gain! There was a ham about 200 miles from me that
did that, and on 80 meters in the early evening, he had a very stout signal
to my QTH.

   You also said, "Components in the audio and phasing sections were
replaced and aligned as necessary to optimize sideband suppression (about 55
dB).   Audio limiter circuitry was modified to eliminate the troublesome
mercury batteries.  Carrier suppression is on the order of 60 dBc."

   I have went through this with the 20A, and never could get those kind of
numbers with any kind of consistency. I had to modify the carrier null
circuit so that the front panel pot (changed from 1K to 5K) was a "fine
adjust", and the "course adjust" was with fixed metal film resistors. This
worked great, but at the carrier null (about 45 dbc) I had components of 60
hertz dominating the RF output at null. The null was stable, but just a
"buzz". I did this on two 20a's, and it came down to those diodes in my
power supply where the reverse recovery glitch couldn't be filtered out
100%. The more I filtered the power the deeper the carrier null until I
discovered another problem. I also have issues with 60 hertz magneticially
getting into the audio modulation transformers from the power supply choke,
and steel chassis. I had some improvement by injecting current into the
chassis out of phase, and of the proper magnitude to in effect buck the buzz
introduced by the choke. Still, 45 dbc was the best I could do. The current
was limited with a 20 ohm 2 W resistor, and injected into the metal flap
holding the balanced modulator diodes. This was with modified 20a's for QRO
output. Tell me about your 100V, and how good it was stock with the carrier
null, and if you did anything to enhance that capability. Is the null
stable?

   Also on my 20A, the SB suppression, was best from 500 hz to 3 Khz. This
was a little harder for me to measure since my test equipment is limited. I
was able to achieve the same suppression from 200 hz to 5 khz with some
simple phasing network tweaks that I empirically derived. So with the 100v,
over what range does the SB suppression maintain 55 db? Does the SB
suppression also vary with RF output power?



Regards,
Jim
WD5JKO

-----Original Message-----
From: central-electronics-bounces at mailman.qth.net
[mailto:central-electronics-bounces at mailman.qth.net]On Behalf Of Radra
Sent: Saturday, April 09, 2005 11:32 AM
To: Central Electronics
Subject: [Central-Electronics] Vintage Ham Shack for Sale - Includes
100V


I completed the restoration of my 100V and am rather pleased with the
result.  Many thanks to those who offered their advice.  While I was at it,
also did a restoration of my HQ-170 receiver.  Out of professional curiosity
I wanted to see how well these vintage items could be made to work employing
modern test equipment and techniques.  Did have to grapple with the question
concerning to what extent I could modify the circuitry and still consider
the equipment "original" and "restored" as opposed to "re-designed".
Finally opted to keep circuit mods to a minimum doing only those necessary
to obtain good performance and safety.  It has been a fun and interesting
project.

Well now that everything is up and running, I have to, once again, deal with
the question of what to do with them.  My QTH is in a draw between three
close-by hills with a mountain a bit farther to south.  CC&Rs prohibit
external antennas.  So HF operation has never been a realistic option here
which partially explains why the ham shack has been in storage for 40 years.
So decided to sell the shack and use the proceeds to obtain some UHF gear I
have had my eyes on.  There is a repeater on yonder mountain.  Am currently
in the process of designing a solid-state UHF amplifier.

If any of you folks are interested, take a look at my eBay listing at
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&category=4675&item=5765697675

Would like to see this equipment find a good home.

Lyman K7LH

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