Hi Max,
I replaced the original audio amp in the R4C with a Velleman audio kit board
with an TDA2003. The Velleman kit # K4001. I believe I paid around $ 15.00.
Works great.
If you're interested I can send you pics.
73 Bert, VE3NR
_
From: drakelist-boun...@zerobeat.net [mailto:
- Original Message -
From: "Max Cotton"
To:
Sent: Wednesday, October 31, 2012 1:18 PM
Subject: [Drakelist] R4C problems
It has now decided not to work anymore, I was listening to
it and gradually the white noise came up, the signal died
and now the preselector is in the wrong plac
- Original Message -
From: "Max Cotton"
To:
Sent: Wednesday, October 31, 2012 11:10 AM
Subject: [Drakelist] R4C Hum and audio transistor
I have a very nice R4C it had a hum with bad audio
distortion so I decided to investigate, whilst taking it
apart I noticed that if I touched th
It has now decided not to work anymore, I was listening to it and gradually the
white noise came up, the signal died and now the preselector is in the wrong
place for each band ie the 40m band livens up around the 80m mark however there
is no signal present, even the cal does not work anymore. I
I must admit this receiver will probably benefit from the Sherwood audio board,
however comparing both my R4C's one is perfect with no hum and very good audio
whilst this one is shushy and has bad hum, maybe the main caps need replacing
but when I couple another cap accross them no change so I a
I tried one, but to my ears, there's too much hiss with some high-end
headphones with the AF control at low settings and even full CCW. I've tried
the LM383, LM380, and TDA2002. The hiss can be reduced with an in-line
attenuator, then running the AF control at a higher level to compensate. I
Max,
I'll get crucified for saying this, but that class A transistor stage was
poorly designed -- and I think we can dispense with the "but they didn't have
cost-effective transistor technology back thirty years ago" as an excuse. A
two-transistor complementary-symmetry PP pair running class A
I have a very nice R4C it had a hum with bad audio distortion so I decided to
investigate, whilst taking it apart I noticed that if I touched the noise
blanker the hum would alter, I removed the NB board and the hum was still
there, I found eventually that the audio transistor had desoldered its
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