[Central-Electronics] Fwd: Re: 6550

Thu Jul 25 16:22:04 EDT 2013

In agree Jim,
  I am getting ready to order a new Choke to replace RFC-1 but not sure 
of what Current rating I should order.
Any of the Guru's on the 100V have a clue? I have found sources for 
22uH, so that doesn't seem to be an issue.
   Jim, I have done the Carrier Null and I can get it down almost 
nothing on the meter.
Right Now I am replacing everything under the Tube Sockets for the 
Finals section. I am about half done.
I did discover an unsoldered connection on one of the tube terminals for 
the ground of C412.

73,
Gordon
N6WK

On 7/25/2013 12:55 PM, Jim Candela wrote:
>
> Gordon,
>
>    I see you were up late tinkering. So getting zilch to 75 watts is a big deal! You might want to enjoy the moment before proceeding. I bet that RF choke, RFC1 is damaged, and a vital part of the circuitry since it seems odd to me to use a choke that low in inductance. A quick scribble suggests that 23uh on 80M has about 550 ohms inductive reactance. Perhaps that amount of reactance compensates for something that the broadband couplers need.
>
>    Maybe you can build up something with similar characteristics? A DC short in that output circuit might be required to make the power meter behave. Or possibly, the power you see with no drive could be the carrier null being a little off?
>
>    I was hoping the 100V/200V guru's would jump in here...This 20A guy is getting out of his element..
>
> Jim
> WD5JKO
>
>
> ________________________________
>   From: Gordon <gordon at n6wk.com>
> To: central-electronics at mailman.qth.net
> Sent: Thursday, July 25, 2013 12:04 AM
> Subject: [Central-Electronics] Fwd: Re:  6550
>   
>
>
>
> Jim,
>    I removed RFC-1 and now I get 75 watts out on 75 meters. but as I go
> higher, each band puts out a little less.
> I think I should be looking for a bad Cap at this point, as removing the
> inductance made more power.
> Another Question, What is up with the little Coax Capacitor thing coming
> off the Band coupler Wafer?
>      I think Tomorrow, I am going to strip everything out from below the
> Finals cage and replace each and every part.
> Another clue might be that my Watts meter shows a reading in transmit,
> even with the Carrier and Power control at fully counterclockwise, and
> the Pot for the Watts turned down as far as it will go.
> I should not be showing anything when there is No output and all
> controls at minimum. I even get a Watts reading in SSB with No carrier
> and no Mic connected...
>
> 73,
> Gordon
> N6WK
>
> On 7/24/2013 7:23 PM, Jim Candela wrote:
>> Gordon,
>>
>> "At first I thought it might be the RFC-1,  mine shows 2.3uH when measured out of circuit"
>>
>>      Looking at the schematic, RFC-1 says .022mh. This converted to uh is 22uh. I'd remove that part temporally and run up the drive. This might explain why you have more power output with increasing frequency.
>>
>> Jim
>> WD5JKO
>>
>>
>> ________________________________
>>     From: Gordon <gordon at n6wk.com>
>> To: central-electronics at mailman.qth.net
>> Sent: Wednesday, July 24, 2013 6:25 PM
>> Subject: Re: [Central-Electronics] 6550
>>
>>
>> Hi George and the Group,
>> George, I have double checked everything you mentioned..Same results.
>>      I tried the new tubes, and as everyone said,  They are NOT the problem.
>> I do have a question though. If I disconnect the Coax from the last
>> wafer that goes to the RF Sampling circuit and the SO-239 connector,
>> Connect my MFJ-259 to the loose end of the Coax  , with a 50 Ohm load in
>> the SO-239, shouldn't the MFJ-259 show 50 ohms? Mine is no where near 50
>> ohms. If I check the dummy load by itself, it is exactly 50 ohms.
>> The only thing on that Coax is the Amps Sampler for the RF output and
>> the SO-239. At first I thought it might be the RFC-1,  mine shows 2.3uH
>> when measured out of circuit, So it appears to be good.
>> I also noticed that the Neutralizing Cap is NOT shown on the 100V
>> Schematic I have in front of me.
>>
>> Gordon
>> N6WK
>>
>>
>>
>> On 7/24/2013 9:48 AM, George Maier wrote:
>>> Hi Gordon:
>>>
>>> Great job on the 100V; glad to see so much enthusiasm for such a worthwhile
>>> project.   Not sure why you are having the RF O/P problems, but your coupler
>>> sequence is correct, and the voltages all seem within limits.  Not sure what
>>> you've done electrically, but here are a few simple things you may want to
>>> consider, if you have not already addressed them.  If you have, please
>>> ignore my drivel:
>>>
>>> 1 - Remove each coupler and apply a high quality contact cleaner to the base
>>> pins and the tap connectors; i.e. - Caig Pro-Gol applied with a q-tip or
>>> Caig pen.
>>> 2 - Same exercise for all of the of the lower stage coil banks, which are
>>> all removable.
>>> 3 - Be sure to replace the 100 mf - 15V cap (C418) across the PA screen over
>>> current relay; they're almost always bad. Also, burnish the relay contacts.
>>> 4 - Check the 10 Ohm resistor (R450) that is in series with the power
>>> control,  to make sure it's not open., and also the rest of the surrounding
>>> connections and circuitry.
>>> 5 - Remove all of the chassis interconnecting plugs (carefully) and clean
>>> them with Pro-gold also.
>>>
>>> Those steps should help to eliminate any flaky stuff, unless of course you
>>> do have bad tubes along the line.  Generally, I agree with the other folks
>>> here, that the PA tubes do not usually fail totally, but hey, it's certainly
>>> possible.
>>>
>>> Keep chugging, Gordon; you'll get there!
>>>
>>> 73, George - W1LSB
>>>
>>>
>>> -----Original Message-----
>>> From: central-electronics-bounces at mailman.qth.net
>>> [mailto:central-electronics-bounces at mailman.qth.net] On Behalf Of Gordon
>>> Sent: Tuesday, July 23, 2013 9:02 PM
>>> To: central-electronics at mailman.qth.net
>>> Subject: Re: [Central-Electronics] 6550
>>>
>>> I am still fighting the no to Low output on my CE-100V.
>>> I have ordered new 6550 tubes, but now I am thinking they are nt the
>>> problem. The tube tester shows both as very strong I am now wondering if
>>> someone has mixed up the Broadband output Coils.
>>> Can anyone tell me what color is correct for each band?
>>> I have Red for 80, yellow for 40, green for 20, blue for 15 and slate for 10
>>>
>>> Is this correct?
>>> I have now discovered that I get more output as I move up in bands. I get a
>>> whole 12 watts out on 20 and 15 meters..LOL Is there a way to test the
>>> center Frequency of each of these broadband output coils?
>>>
>>> Thanks,
>>> Gordon
>>> N6WK
>>>
>>>
>>>
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