[Elecraft] P3 and HQ-170A

[Phil Hystad]

Alan,

Thanks.  Looks like I might do some experimenting later but probably won't have the time until Summer.

73, phil, K7PEH


On Feb 9, 2012, at 10:11 PM, Alan Bloom wrote:

> I downloaded the HQ-170A schematic and took a look at the schematic.  It
> looks like the 455 kc output is taken directly from the plate of the
> second mixer through a 10 pF (oops, I mean 10 mmF :=) capacitor.
> 
> Since 10 pF has 35 kohms reactance at 455 kHz, you'll probably need a
> buffer to drive the P3's 50-ohm input.  You could use a cathode follower
> (if you want to be authentic) or an FET source follower (with clamp
> diodes at the input to protect the gate from voltage transients).
> 
> Let us know how it turns out.
> 
> Alan N1AL
> 
> 
> On Thu, 2012-02-09 at 21:03 -0800, Phil Hystad wrote:
>> So, I get my Hammarlund HQ-170A out of the storage garage because I
>> got a re-tubing kit and I am finally going to replace some or all of
>> the tubes.  The HQ-170A works but audio is a little on the weak side
>> and sensitivity could be improved.  I will do the tube thing first and
>> then maybe consider some alignment experiments.
>> 
>> But...
>> 
>> I noticed on the back, something I have never noticed before that I
>> remember, is that there is a 455 KC (well, it says KC) IF output.  I
>> am guessing I might be able to plug this into the P3.
>> 
>> Am I guessing right or is there some other stuff I might have to
>> consider -- such as signal level (voltage) or other things.
>> I don't suppose anyone out there in Elecraft-land has hooked their
>> HQ-170A receiver up to the P3.  If so, let me know how it works.
>> 
>> 73, phil, K7PEH
>> 
> 
>