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Help with Hammarlund HQ129X - What size paper capacitor is this?



 
 
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  #1  
Old February 22nd 12, 11:45 PM posted to rec.radio.amateur.boatanchors
Gregory Mosher
external usenet poster
 
Posts: 1
Default Help with Hammarlund HQ129X - What size paper capacitor is this?

Boatanchors,

So I bought a HQ129X at a hamfest last spring as a project. Seller had
started a recap job & decided to quit and sell it - price was right
for me. When I got the radio home I plugged it in - DOA. I found a
bad power cord, spliced in a temp and fired it up - the loudest HUM
I've ever heard - holy crap.

Anyways - I know how to use a soldering Iron but I'm in no way an
electronics person - decided to see what I could do - I bought a recap
kit for the receiver online and dived in this past weekend. Replaced
the electrolytic can, then all of the paper caps except one - more on
this one paper cap later.

I then replaced the power cord with a new 3-prong cord and fired the
beast up. No Hum (good). In fact the receiver works very well on MW
and SW bands, quite sensitve and fairly selective - I was pleasantly
suprized.

Anyways - back to that one paper cap - Any identification on rating
is gone from the cap itself - so I donlt know what to replace it with?
I supose I could just leave it but I noticed it gets very hot with
radio operation - the ones I replaced do not - so I suppose it's bad
and should be rerplaced? If I remove the cap the radio is dead -
Perhaps somone familiar with these radios can help me identify the
rating of this cap? It's of different physical size to the others I
replaced. The cap is direct connected between one of the pins on the
VR105-OC3 tube and the Relay connector on the back of the Chassis. I'm
not a wiz with reading schematics - Even though I identifed the tube
and relay in the schematic I was unable to discern the right cap in
the diagram.... Can anyone figure out the ratings of this cap from my
description of it's location and let me know?

Regards,

Gregory.
  #2  
Old February 23rd 12, 12:02 AM posted to rec.radio.amateur.boatanchors
Rich Greenberg
external usenet poster
 
Posts: 32
Default Help with Hammarlund HQ129X - What size paper capacitor is this?

In article ,
Gregory Mosher wrote:

Anyways - back to that one paper cap - Any identification on rating
is gone from the cap itself - so I donlt know what to replace it with?
I supose I could just leave it but I noticed it gets very hot with
radio operation - the ones I replaced do not - so I suppose it's bad


It MAY not be a capacitor at all, From your description, I would
suspect a wirewound power resistor which would get somewhat hot in
normal operation.

You will have to locate it on a schematic to be sure.

--
Rich Greenberg Sarasota, FL, USA richgr atsign panix.com + 1 941 378 2097
Eastern time. N6LRT I speak for myself & my dogs only. VM'er since CP-67
Canines: Val,Red,Shasta,Zero,Casey & Cinnar (At the bridge) Owner:Chinook-L
Canines: Red & Max (Siberians) Retired at the beach Asst Owner:Sibernet-L
  #3  
Old March 1st 12, 04:31 PM posted to rec.radio.amateur.boatanchors
Richard Knoppow
external usenet poster
 
Posts: 530
Default Help with Hammarlund HQ129X - What size paper capacitor is this?


"Gregory Mosher" wrote in message
...
Boatanchors,

So I bought a HQ129X at a hamfest last spring as a
project. Seller had
started a recap job & decided to quit and sell it - price
was right
for me. When I got the radio home I plugged it in - DOA.
I found a
bad power cord, spliced in a temp and fired it up - the
loudest HUM
I've ever heard - holy crap.

Anyways - I know how to use a soldering Iron but I'm in no
way an
electronics person - decided to see what I could do - I
bought a recap
kit for the receiver online and dived in this past
weekend. Replaced
the electrolytic can, then all of the paper caps except
one - more on
this one paper cap later.

I then replaced the power cord with a new 3-prong cord and
fired the
beast up. No Hum (good). In fact the receiver works very
well on MW
and SW bands, quite sensitve and fairly selective - I
was pleasantly
suprized.

Anyways - back to that one paper cap - Any identification
on rating
is gone from the cap itself - so I donlt know what to
replace it with?
I supose I could just leave it but I noticed it gets very
hot with
radio operation - the ones I replaced do not - so I
suppose it's bad
and should be rerplaced? If I remove the cap the radio is
dead -
Perhaps somone familiar with these radios can help me
identify the
rating of this cap? It's of different physical size to the
others I
replaced. The cap is direct connected between one of the
pins on the
VR105-OC3 tube and the Relay connector on the back of the
Chassis. I'm
not a wiz with reading schematics - Even though I
identifed the tube
and relay in the schematic I was unable to discern the
right cap in
the diagram.... Can anyone figure out the ratings of this
cap from my
description of it's location and let me know?

Regards,

Gregory.


This thing is R-54, a power resistor, its supposed to
run hot.
The HQ-129-X is an excellent receiver despite being an
economy model.
There is a decent handbook on BAMA.
It was the post-WW-2 version of the HQ-120-X, which was
the first receiver with the Hammarlund patented crystal
filter. The model number comes from the originally intended
price: $129, it didn't sell for that for very long and
eventually the price about doubled.
The IF uses a combination of overcoupled transformers
and critically coupled links to give a relatively flat
bandpass and better skirt selectivity than is usual for
receivers of this sort. Its main shortcoming is relatively
poor RF selectivity (image rejection) from having only one
RF stage, however the image rejection is still better than
most receivers with a single RF due to the good design and
high quality coils used.



--
Richard Knoppow
Los Angeles
WB6KBL



 




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