[Collins] Fwd: [R-390] OT: 30L-1 transformer question

[Dr. Gerald N. Johnson]

Possibly the 20% lower plate voltage protected the 811As from over 
dissipation at idle, or reduced the power output to protect the loading 
capacitors or the whole tank circuit, especially on RTTY. Or just 
brought the plate voltage back to the design value when run on 127/254 
volts modern high line voltage compared to 112/224 under load which was 
more common when the rig was designed though that might have been more 
easily achieved by adding a few primary turns and rating it at 120/240 
or 125/250 instead of 115/230.

Was there a mod that added power supply filter capacitor while reducing 
the bleeder current, and so raising the plate voltage? This transformer 
might compensate for that.

73, Jerry, K0CQ, Technical Adviser to the Collins Radio Association.

On 6/4/2011 5:36 PM, Glenn Little WB4UIV wrote:
> This was posted on the R-390 group.
> Anyone here have any ideas??
>
> Thanks
> 73
> Glenn
> WB4UIV
>
>> Delivered-To: r-390 at mailman.qth.net
>> To: r-390 at mailman.qth.net
>> From: frankshughes at aim.com
>> Date: Sat, 4 Jun 2011 17:22:14 -0400 (EDT)
>>
>>
>> Hi,
>> This is a little off topic, however, the amplifier is used w/ the
>> Collins 32S-3 transmitter, which
>> is connected via a relay to the "break-in" on my R-390A. (Close as I
>> can get to forum content.)
>>
>>
>> Hoping someone here might know about obscure Collins technology.
>> (I'll try the Collins forum with this question too)
>>
>>
>> Anyway, I have a spare transformer for my Collins 30L-1. The
>> transformer is a custom winding done by
>> PETER W. DAHL, now being sold by HARBACH ELECTRONICS.
>>
>>
>> The Harbach guys have no idea what the thing I have is wound for;
>> "That was something Pete made years ago"
>>
>>
>> Any guesses as to what situation is the lower voltage/current unit
>> designed to solve?
>>
>>
>> 73
>> KJ4OLL
>>
>>
>> COLLINS 30L-1 ADVERTISED UNIT (standard transformer, for comparison)
>> CORE) EI-175 X 3" 29GA M6X STYLE #) 02 E-I LAMINATED CORE
>> PR) 115/230 VAC 50/60 HZ 1 PH
>> S1) 650 VAC 0.7A CCS
>> S2) 120 VAC @ 0.020A CCS
>> S3) 6.3 VCT @ 16A CCS
>> DM) HT = 4.375 WT = 5.250 DT = 5.205 MD = 4.125 MW = 4.375 WEIGHT) 19 LBS
>>
>>
>>
>>
>> COLLINS 30L-1-1 MODIFIED SEC 1 VOLTS&  SEC 2 CURRENT (this is the
>> custom wound unit)
>> CORE) EI-175 X 3" 29GA M6X STYLE #) 02 E-I LAMINATED CORE
>> PR) 115/230 VAC 50/60 HZ 1 PH
>> S1) 550 VAC 0.7A CCS
>> S2) 120 VAC @ 0.100A CCS
>> S3) 6.3 VCT @ 16A CCS
>> DM) HT = 4.375 WT = 5.250 DT = 5.205 MD = 4.125 MW = 4.375 WEIGHT) 19 LBS
>
>