Finally found the intermittent static in my R4A by poking around with a plastic
tuning tool, revealing the problem was on Board 3, with a (second) bad solder
connection, this time at Q8. This was the second bad solder joint on that
board, so removed the board and reflowed ALL of the joints.
All,
Well my luck or lack thereof continues... I pulled the 6HS6 and then
referenced my Eico 625. Of course the 6HS6 isn't mentioned anywhere in any of
the charts I have. So, based on some results of a search, tested it as a 6AU6
and then a 6HR6. Former showed good, latter showed marginal,
I've checked all of the tubes with my old emission tester, all test good
except for the OA2 which lights up but tests bad. Not sure how valid that is.
And with V8 removed, the resistance at pin 6 is still 15k rather than 90k per
the manual. I'm in process of resistance checking the rest of the
Hello Gary,
Yes, that is what I've concluded too though haven't confirmed with measurements
yet. I know at one time you repaired Drake equipment (maybe you still do), so
would appreciate any words of wisdom about finding and correcting a short in
the B+. Nothing obvious on visible
Well, my nose detected burnt smell in vicinity of T4. R61, a 150ohm 1/2
resistor in the 250 volt line to V8's plate is burnt to a crisp, resistance is
zero. But why? Resistance to ground on V8 pin 5 is 15k per spec. But pin 6
screen grid resistance to ground it 15k, vs 90k spec.
Any
My T-4X quit working today, the 250V supply was gone. Filament, bias, and 650V
supply normal. On investigating the AC-4R board in the AC-4, found two
parallel 5W 200ohm metal oxide resistors in the 250V supply circuit OPEN.
Suspected a shorted capacitor, but the cap is not shorted. Anyone
I use D-104 microphones for my Drake T-4X, and for various old rigs. Have
three, two with original cartridges, the third rebuilt with a kit that included
a kobitone cartridge. While it worked for awhile, yesterday while using it on
AM with the T-4X the required transmitter gain was excessive,
I'm trying to fix my R-4A, looking for help diagnose and repair. Unfortunately
I don't own a signal tracer or an oscilloscope.
When initially powered on, the R-4A works normally for about 5 minutes. Then,
static will build over period of about one minute, with no received signal,
followed
I bought a 2mL container of Deoxit 100% together with order for couple of
tubes. So far, I have yet to use Deoxit on anything, previous postings have
made me leary. I'm understanding one drop on the stationary contact, then
rotation? Then using industrial qtip to pick up the results?
For about 20 minutes after being turned on, R-4A ehibits static building from
low to high volume over about 10 seconds, followed by a pop, then repeat.
AGC setting and band selected makes no difference. Happens with or without
signal input. After about 20 minutes, the static goes away and
I own a Drake 2B which recently seems to take about an hour to achieve stable
operation. By that, I mean listening to a cw signal, the tone will sound like
a sick canary for about an hour after turning on the receiver. After that,
operation is normal. This behavior happens regardless of band
With my R4A s/n 6759, have distortion of a sideband signal when RF gain control
at maximum, AVC on fast. CW signal is normal, and there is no distortion
with the AVC off or on slow or with RF gain lower. I'm recalling the AVC
setup can be difficult to get right, appreciate any advice before
I've become somewhat interested in AM again, had been using my T-4XB on 40M, no
issues. Curious how my T-4X would work on AM, swapped it with the T-4XB.
While the T-4X works fine on CW and SSB, on AM, keying the microphone causes
the plate current to go to maximum regardless of drive
I changed out V11 with the 6AU6 from the T-4XB, when the microphone is keyed,
plate current climbs to 250 ma then drops back to idle current (70 ma) after
1-2 seconds. So, evidently the problem isn't a bad V11.
73, Curt KB5JO___
Drakelist
Most recent purchase was a mint Omni C with a broken crystal carrier. They
are no longer available from any source, including the factory. So, the C
won't function on 30M. The on-off switch was also broken, not really an issue
because use the PS switch anyway, but those not available
I own and enjoy both. Drake 4 line and 2B. Ten-Tec 509, 540, 544, 545, 546,
588. All except last purchased used of course. Only ones needing work were the
Drakes and the newest Ten-Tec. The 588 recently revisited the factory for
repair when 3 years old, of course Ten-Tec fixed it
My 2B suddenly quit this afternoon. Calibrator heard on 80M, weakly on 40M,
nothing above 40M. Audio hiss on all bands. Ideas?
73, Curt KB5JO
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Drakelist mailing list
Drakelist@zerobeat.net
Awhile ago my R4A stopped receiving SSB/CW. With Garey's help, determined C173
was bad. Voltage measurements showed low voltage to Q6 etc, found R139 was 470
ohms per schematic that came with my R4A, someone had obviously replaced that
resistor. Except, the schematic did NOT match my s/n
I'm trying to determine whether the transistor 50 kHz BFO is functioning in an
R4A. I don't think it is, but don't own a scope. Is there a way to verify
whether it is oscillating?
73, Curt KB5JO
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Drakelist mailing list
For awhile now, my Drake 2B received CW with unstable frequency for about 30
minutes after being turned on. The received note is unstable. Any ideas where
to start troubleshooting this. Unfortunately, after warming up everything is
fine.
___
While working on my 2B totday, had an opportunity to use the 2B/2BQ CDs
purchased awhile ago from you. The receiver had started a severe hum when
powered on, so decided it was time to replace the caps before something worse
happened. The kit from Hayseed Hamfest included a small 10uf cap
Regarding the bias setting of 70ma, what is the impact of lower bias setting (
say 60ma )?
Regarding neutralization, this transmitter seemed to need neutralizing based on
behavior on 40M. On 15M, the neutralization seems exactly on ( maximum
output at minimum plate current ). What would
I'm sick of working on this MN4C with B1000, life is too short. It worked fine
until it didn't and can't seem to identify what the problem is. Make an offer
offlist if interested before I put it on the auction site.
73, Curt KB5JO
___
Drakelist
Further this, the kind to finals procedure is what I have always followed
even before owning Drake. In fact, that procedure was what I used in the early
60s as a Novice.
The main issues for me is time and cost for changing out final tubes. I'm
never hard on them, always watch the bias,
After trying several pairs of 6JB6 tubes with similar behavior ( PA current
very sensitive to drive control position), concluded the trouble couldn't be
the PA tubes. Swapped the driver tube with one in my T-4XB, now the plate
current behaves normally, that is increases smoothly with
When I but the suspect driver tube into the T-4XB, it performed fine for about
5 minutes, then started acting just as in the T-4X. So, suppose this tube is
bad. Will order another to see.
73, Curt KB5JO
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Drakelist mailing list
Recently using my 2B with a T-4XB, noticed the tuning knob skirt divisions seem
off from the sliderule devisions. For example, moving from 7.100 to 7.200, 10
major divisions on the linear dial requires is 11 major divisons on the knob
skirt. One lnob turn is 4 major disvisions on the skirt.
Hope the list is working today. I own a 2B, which recently tried to use
with my T-4XB. Muting isn't adequate. That is, sometimes I hear signal
breakthrough. Does this sound like a tube problem in the Drake. The T-4XB
paired with my R-4A works FB so the problem seems to be in the 2B
73,
Trying to perform the carrier balance adjustment, the control has
no effect and the output with gain full ccw is zero no matter what. I am
getting output
in LSB, USB, and CW when operating normally with key or microphone.
I went through carrier oscillator/filter match/ and balance
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