It's been a while since I had one to repair. I do recall that the carrier
oscillator alignment must be made to very accurate results. I try to obtain
something better than 1 Hz accuracy, ideally to 0.1 Hz. Same true for the
Paragon BFO's and the Omni VI series BFO's as well.
Since these aren't well compensated, let the radio warm with covers loose
for at least 30 to 45 minutes before adjustments are made. Then put the
covers back on and wait a suitable period and measure the frequency again.
Be sure to use test equipment and test probes that do not load the circuits.
I typically use a 10X low capacity scope probe on the input to my counter.
And yes it could be the 2.4 KHz filter has changed. Without doing a sweep
of the filter, hard to exactly say.
73
Bob, K4TAX
----- Original Message -----
From: "Barry N1EU" <barry.n1eu@gmail.com>
To: "Discussion of Ten-Tec Equipment" <tentec@contesting.com>
Sent: Friday, October 26, 2012 7:38 PM
Subject: Re: [TenTec] Corsair II PBT Question
Be sure to perform the carrier oscillator alignment (BFO) for SB-N and
SB-R before you do the PBT adjustment.
73,
Barry N1EU
On Fri, Oct 26, 2012 at 5:12 AM, K4MT <k4mt@yahoo.com> wrote:
My Corsair II has a problem with the PBT adjustment. I can not get the
SB-N and SB-R to sound the same. When I adjust coil L4 the closest I can
get is with the slug all the way to the top which raises the frequency f
the 15.3012 crystal. I measured the frequency range of the 15.3012
oscillator and it varies from 15.3012 with the PBT control full CW to
15.2969 full CCW, I found that SB-R audio quality is very tinny. I was
wondering since the crystal reads 15.2969 with PBT CCW (no voltage on the
varactor) means the crystal is too low in frequency. Tentec wants 30
shipped so before I order one I was wondering what the experts on this
group think.
I have aligned the carrier oscillators so that is not the problem. It is
the same on all bands and all crystal filters ( I have 2.4, 1.8, 500 and
250). Do you think the 15.3012 crystal is out of specs or is it something
with the 2.4 9 MHz filter?
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