[Hammarlund] HQ-129-X Question

[Richard Knoppow]

----- Original Message ----- 
From: "Richard Knoppow" <1oldlens1 at ix.netcom.com>
To: <hammarlund at mailman.qth.net>
Sent: Thursday, November 25, 2010 11:19 AM
Subject: [Hammarlund] HQ-129-X Question


>     I've finished tuning up my HQ-129-X. I find the
> calibration of the band spread is just awful especially 
> for
> 80 and 40 meters. The error becomes progressively larger 
> as

     I've been through all suggestions and non seem to be 
the problem. I checked the mechanical alignment of both main 
and band spread tuning capacitors, neither shows any sign of 
de-centering or other mis-alignment. I check the centering 
of the main tuning cap using feeler gauges. The spacing of 
the BS sections is too large for this technique but can be 
done by tracing over the tops of the plates and measuring 
the marks. I also made sure the stops of both dial were 
correctly set.
    The main tuning is fairly close, the BS is close on 20 
and fair on 10,  but not on 80 or 40. I suppose the actual 
error is not large but more than I would expect. I suspect 
the errors on the main tuning are from slightly drifted 
padding caps.
    I've done a careful alignment, making sure that the LO 
was above the signal frequency on all bands. It will go on 
either side on at least the top two bands, not sure if there 
is enough range for the others. In any case I double checked 
its position using another receiver with excellent 
calibration (R-388) to listen for the LO.
    The AVC problem I mentioned in my first post is probably 
not actually a problem but due to the limited S-meter range. 
The RX seems able to handle local broadcast stations other 
than the nearby flame thrower 50K one and nothing can handle 
that one, its nearly strong enough to run a loudspeaker off 
a crystal set:-)
    All in all this is a nice RX, quite stable and works 
well for SSB. It turns out that I have an actual matching 
speaker for it. Its the speaker I usually use with my R-388. 
I have some other "communications" type speakers but this is 
the best sounding of the bunch. Mine has a Jensen speaker in 
it.
    A puzzle, there is a low value cap across the speaker 
winding of the output transformer. Its lifted when earphones 
are attached. The only reason I can think of for this cap is 
to provide some sort of load when no speaker or phones are 
attached. While its too low in value to affect the high end 
response of a speaker it might cut down the highs for high 
impedance phones so its lifted. I wonder if I am right abuot 
it.


--
Richard Knoppow
Los Angeles
WB6KBL
dickburk at ix.netcom.com