Re: [Drakelist] Drakelist Digest, Vol 35, Issue 15
Drakers, I too have the same problem and was going to do what Garey suggests, but had other stuff pop up (weddings, health, family, and PSK-31 bug bite), so have not tried anything yet. Waiting with baited breath to what Joe finds. I made my own cables and thery are the same total capacitance spec'ed by Drake (shorter) using the pF/foot data. Thanks Joe and others. Jim Joe Loverti wrote: When I tune up using the T-4XB PTO on 40 meters, I'm getting about 60 watts maximum. When I tune up using the R-4A PTO the power output is 95+ watts maximum. There's also about a 10 db difference in receive between the two units, the R-4A being the stronger receive of the two. I am using original Drake interconnect cables between the two units. I'd expect some difference between them, but this seems excessive. Any thoughts? WW8X Joe -- Message: 6 Date: Sat, 14 May 2011 00:01:56 -0400 From: Joe Loverti ww8x@gmail.com To: drakelist@zerobeat.net Subject: [Drakelist] Power output difference between T-4XB and R-4A PTO's Message-ID: BANLkTi=dfryipzo+y_qqo0vsdwzzrpc...@mail.gmail.com Content-Type: text/plain; charset=iso-8859-1 Curt, Thanks for the answer. I'm using the cable with metal tag for the injection. I haven't tried tuning up the T-4XB without it plugged in -- I'll give it a try an see what gives. If there's no difference, that would eliminate the cable as the problem. WW8X Joe ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
[Drakelist] Adding filtering capacitor
Is there any advantage of adding a large filtering capacitor if there is no issue with the radio? Is a larger capacitor worthwhile and will it result in smoother power? ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] Adding filtering capacitor
It depends on what the application is. DC filtering in a rectifier circuit? Bypass for a grid/cathode? Coupling capacitor for audio stages? Etc. etc. If indeed it is for filtering, and in a rectifier circuit, it can improve regulation if the power supply is unregulated, it can reduce the ripple, etc. BUT you don't want to go too large or the surge current may exceed the rating of the diodes used for rectification. -Original Message- From: Neil M Califano cchange...@yahoo.com To: Drakelist@zerobeat.net Sent: Sat, May 14, 2011 11:09 am Subject: [Drakelist] Adding filtering capacitor Is there any advantage of adding a large filtering capacitor if there is no issue with the radio? Is a larger capacitor worthwhile and will it result in smoother power? ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
[Drakelist] TR-4C Bias
I have a TR-4C that I cant set the bias on. When adjusting the bias control on the power supply it has no effect on the radio. I have 2 power supplies and both have no effect. I can remove the bottom cover from the supply and set the bias to the proper - voltage using my volt meter but it does not set the bias on the radio. Where do I start looking. Tnx in advance for the helpde Bill..KY4U PS. I have checked the cable from both supplies and the connector on the radio for loose connections but nothing wrong there.Bill___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] TR-4C Bias
Bill - I'm guessing here, since you didn't specify. Do you mean when you key the transceiver you have NO PLATE current, or LOTS of PLATE current??? Assuming you have NO PLATE current, which is most likely, consider that the PA tube normally want to draw as much current as possible when keyed, the BIAS is to LIMIT that current. If this is the case, then the transceiver PA is not really being keyed. Since you have eliminated the PS as the problem, there are only a couple of things to check. First, has the TR-4C been modified for use with TC-2 or TC-6? If it has, then there must be a jumper connected between two jacks on the upper rear panel to apply Screen voltage to the PA. IF not, then 'something' is open. IF the voltages on the PA tubes are correct, e.g., 650 VDC on plate caps, 260 VDC on Screen pins, and the Cathode is grounded, the PA WILL draw maximum current. Pin 3 of each final tube goes to a 15 ohm, 1W resistor. All three resistor leads then go to RFC2. The other lead of RFC2 connects to a ceramic feedthrough on the shield wall to R45. The other lead of R45 goes to a relay contact that is grounded in transmit. If this circuit is unbroken, including the relay contacts closing, and the Plate and Screen voltages are correct, the PA WILL draw current. Regardless of ANY other fault or problem in the transceiver. 73, Garey - K4OAH Glen Allen, VA Drake 2-B, 2-C/2-NT, 4-A, 4-B, C-Line and TR-4/C Service Supplement CDs www.k4oah.com Billy Loyd wrote: I have a TR-4C that I cant set the bias on. When adjusting the bias control on the power supply it has no effect on the radio. I have 2 power supplies and both have no effect. I can remove the bottom cover from the supply and set the bias to the proper - voltage using my volt meter but it does not set the bias on the radio. Where do I start looking. Tnx in advance for the helpde Bill..KY4U PS. I have checked the cable from both supplies and the connector on the radio for loose connections but nothing wrong there.Bill ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] TR-4C Bias
What does the PA current read with the RF gain at zero and the PTT switched to transmit? If it is high, then that might suggest an issue with the circuitry at the finals. Hard to guess if it is low and not adjustable. Curt KU8L Billy Loyd wrote: I have a TR-4C that I cant set the bias on. When adjusting the bias control on the power supply it has no effect on the radio. I have 2 power supplies and both have no effect. I can remove the bottom cover from the supply and set the bias to the proper - voltage using my volt meter but it does not set the bias on the radio. Where do I start looking. Tnx in advance for the helpde Bill..KY4U PS. I have checked the cable from both supplies and the connector on the radio for loose connections but nothing wrong there.Bill ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
