[MRCA] [MMRCG] GRC-19 on the air

Sun Jan 4 16:18:55 EST 2026

Hi Ray,

I worked for IBM from 1965 until 1976 and among the things I plucked out of
the trash were two 130# power supplies that mimicked the PP-1104, 12V at 100A
or could have been wired for 24V at 50A.  The transformers were ferroresonant
units and although they had completely fried the rectifiers and large cap
banks were fine.  The ferroresonant design automatically causes a safe
output voltage collapse in response to a severe overload and also gives  a
well regulated almost square wave output for normal loads.  Really heavy
though.  The Acme transformers were 100# plus some heavy AC caps.

Ah the good old days when I could work with such lovely and heavy stuff.

73,

Clare. N2RJB

On Sun, Jan 4, 2026 at 3:31 PM Ray Fantini via groups.io <RAFANTINI=
salisbury.edu at groups.io> wrote:

> Cool, did not know the PP-8474 was up to the task of inrush on a dyno
> version of the T-195, I use the 8474 on everything else like working on
> GRC-106 and PRC-47 sets without issue. The PP-8474 is an amazing box.
> Have a huge Heavy PP-1104 that uses some weird form of transformer
> lamination control for regulation that will provide 12 volts at 100 amps or
> 24 volts at 50 amps that has no issues driving high inrush loads, just
> watching the current meter go all the way over and the voltage drop way
> down on the switching supply like the 8474 can be unnerving! But when it
> comes to the 1104 think I would be able to DC Arc weld with that box and
> not hurt it.
>
> RF
> ------------------------------
> *From:* MMRCG at groups.io <MMRCG at groups.io> on behalf of Meir Ben-Dror WF2U
> via groups.io <wf2u=ws19ops.com at groups.io>
> *Sent:* Sunday, January 4, 2026 3:15 PM
> *To:* scottjohnson1 at cox.net <scottjohnson1 at cox.net>; mmrcg at groups.io <
> mmrcg at groups.io>; w6iee.73 at gmail.com <w6iee.73 at gmail.com>; mmrcg at groups.io
> <mmrcg at groups.io>
> *Cc:* mrca at mailman.qth.net <mrca at mailman.qth.net>
> *Subject:* Re: [MMRCG] GRC-19 on the air
>
>
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> Ray and all,
>
> Both the HV and LV dynamotors in the T-195 (I have several) I use  from
> time to time on the regional 80 meter AM net on the Old Friends' Net (3715
> kHz, Tuesdays and Thursdays at 8:00 am and Sundays at 4:00 pm Eastern,
> covering NC, SC, GA and TN) are the old mechanical ones.
> I power my whole GRC-19 setup from the PP-8474 and it starts the
> dynamotors without a hiccup. The 60 amp meter kicks up to the top stop, it
> takes about 2 seconds for the HV dynamotor to spin up to speed, while the
> dial lights dim a little, the voltmeter initially dips a little, then the
> ammeter goes down to the steady-state current of 35 amps with 100 watt
> carrier output from the T-195, and the output viltage settles again at 28
> VDC. With modulation the ammeter fluctuates a little bit, but because the
> meter movement is dampened,  it shows the average, it doesn't deviate
> visually more than a couple of amps plus or minus.
> My T-195B with both  HV and LV solid state inverters used to run around
> 20-25 amps, but lately it has a nasty 400 Hz riding on the carrier,  which
> must be coming from the small 400 Hz inverter that feeds the fan motors in
> this B model, maybe either a bad ground somewhere or one or more faulty
> feedthrough capacitors. Because of this on AM the 400 Hz noise gets on the
> audio also, and modulates the already noisy carrier, increasing the steady
> state current draw on the 28 volt supply by several amps.
> I'll have to open it up and find the source of the problem, because that
> transmitter is unusable this way.
>
> 73, Meir WF2U
> Landrum, SC
>
> Get BlueMail for Mobile <https://bluemail.me/download/>
> On January 4, 2026, at 13:19, Ray Fantini via groups.io <MMRCG at groups.io>
> wrote:
>
>
> At the time that radio was designed Collins was in love with four band
> multipliers and the PTO with the idea that nothing beats the stability or
> quality of there sealed PTO.
> The PTO operates in a fixed band; think on the T-195 it's 1.5 to 3.0 MHz,
> and they have a system of four buffer multipliers to get the other
> frequencies. Start by checking the accuracy of the PTO on 2.00 MHz and
> that’s where you want to make any mechanical correction. Any error in band
> one will be multiplied in the higher bands! Don’t try changing to make
> something look correct on eighty or forty, do all alignment on band 1. More
> modern transceivers used converters and the like, but you were unable to
> get the wide coverage without using that approach back in the fifties.
> Collins used the same approach on the T-368 and ARC-38
> Another thing to look at is if you have the solid-state inverters or the
> mechanical dynamotors. There is a huge advantage in having the solid-state
> inverters over the mechanical dynamotors when it comes to starting current.
> Talked with old timers who used the GRC-19 back in the sixties and they
> tell me it can easily slow down if not outright stall a M-38 unless you
> were driving over thirty miles an hour or had the throttle set way high
> when keyed.
> With the solid state inverters, you can run all day long with a PP-8474
> power supply and with the dynamotors if you can find a PP-1104 battery
> charger – Power supply that will do the job. The PP-1104 can also do fun
> stuff like start an M-151 or M-38 or your daily driver. They can usually be
> had for cheap but at 110 Lbs. you don’t want to ship it.
>
> Ray F/KA3EKH
>
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