Re: T4XB/R4B Transceive problem
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There is no 50KHz in the transmitter.
BUT, Richard points out an important thing.? 50KHz in the R-4s are adjustable... not by much, but with component
drift or other problems, the 50KHz BFO MIGHT be off. Also Steve's method of using a receiver is better than hooking in a frequency counter.? The counter can load the circuit and force it off frequency.? I have lately been using my tinySA, just lay a probe over the circuit and see everything. Don't give up, let us know what you find, 73, Gary WB6OGD
On Sun, Dec 22, 2024 at 1:11?PM Richard Knoppow via <1oldlens1= [email protected]> wrote: ? ? Its been a long time since I aligned my T4XB/R4B but I think maybe
there is an alignment problem, not a bad filter or bad crystal. The idea
is to set the? 50 Khz LO so that the carrier falls at the same place on
the upper and lower slopes of the filter. Can by done by ear or by
measuring the amount the carrier is reduced from the peak. This is the
LO in the transmitter. The LO in the receiver is set to match it using
C-61 to get the "Tweet" zero beat. The color coded crystals were meant
to give matched temperature drift but with the age of the crystals that
is probably no longer valid and is, in any case, not a big deal. It may
be necessary to reset C-61 occasionally. In my twins the colors do not
match or maybe there are no colors but the zero beat doesn't change.
? ? ?Because the? 50 Khz band pass filter in the R4B is adjustable the
exact LO frequency does not matter. The adjustment is given in the
_transmitter_ book even though its for the receiver.
? ? ?I just think the crystal is probably OK and this is a red herring.
? ? ?I've found that? you must study both handbooks carefully, read
everything even if you don't think its relevant. Also, if you don't have
Gary Barrell's (never sure of the spelling) CD for the B line GET IT,
and read or at least look at everything in it.
? ? ?I think these are very good pieces of equipment and the performance
is excellent.
? ? ?Due to work done on the house (which I rent) I lost my workshop, no
longer power there. Puts a crimp in my work. Will fix this eventually.
Otherwise I would poke at my twins to see what I can find.
On 12/22/2024 12:47 PM, Steve Wedge, W1ES/4 via wrote:
> I¡¯ve seen mixed ones like this before. Just production variations. Set
> C2 to exactly 5645.000 and check the results.
>
> The method from the manual is a pain, quite honestly. Hans didn¡¯t have
> access to lab grade counters back I. The day.
>
> Steve Wedge, W1ES
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Richard Knoppow
Los Angeles
WB6KBL
SKCC 19998
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Gary WB6OGD