[ARC5] Fw: Model 19 MKll

Henry Mei'l's meils at get2net.dk
Wed Feb 24 07:12:53 EST 2010 

Could u mail scans of the circuit diagrams of your voltage regulators? - 
especially your HB HV regulator.

I admit that I also modify my vintage surplus as little as possible and 
retain any removed parts so that they can be put back, if desired.

Make it at point to leave outer appearance as pristine as possible.
Henry

----- Original Message ----- 
From: "Dennis Monticelli" <dennis.monticelli at gmail.com>
To: "Discussion of AN/ARC-5 military radio equipment." 
<arc5 at mailman.qth.net>
Sent: Wednesday, February 24, 2010 5:13 AM
Subject: Re: [ARC5] Fw: Model 19 MKll


> If your feed-through signal is 50dB down that's doing well.  Spurs and
> harmonics should also be at least 50dB down.
>
> I use all the regulation techniques you mentioned, Henry.
>
> The Osc is regulated by two stacked 105V reg tubes. The PA Screen is
> regulated by stacking a zener on top of the regulator tube stack and then
> buffering with a single transistor.  The PA Plate uses a homebrew 
> transistor
> feedback regulator because a triode pass device wouldn't fit on the 
> chassis
> as a retrofit.
>
> Dennis
>
> On Tue, Feb 23, 2010 at 3:12 AM, Henry Mei'l's <meils at get2net.dk> wrote:
>
>> OK Dennis
>> You're right about the poor match-capacity path  between osc and PA BUT
>> I've
>> been told in several QSOs that my backwave was quite readable
>> though never told how many S-units or dB down. Do you use VR tubes, 
>> zeners
>> on all B+ voltages and or a triode regulator for the plates?
>> I also use a foot switch when I operate with my TCS - when not in QSK 
>> mode.
>> Thanks for the info.
>> Henry
>>
>> ----- Original Message -----
>> From: "Dennis Monticelli" <dennis.monticelli at gmail.com>
>> To: "Discussion of AN/ARC-5 military radio equipment."
>> <arc5 at mailman.qth.net>
>> Sent: Tuesday, February 23, 2010 10:56 AM
>> Subject: Re: [ARC5] Fw: Model 19 MKll
>>
>>
>> > Good questions, Henry.  I will try to answer them and also pass along
>> some
>> > other details on the setup to satisfy your curiosity.
>> >
>> > With a cathode keyed PA the forward transfer of oscillator energy 
>> > through
>> > the tube inter-electrode capacitance into the output tank (which is a 
>> > bad
>> > impedance match to this leaking signal) is normally rather low and in 
>> > my
>> > particular situation measured well within acceptable FCC limits.
>> >
>> > As for the adjusting for the difference in frequency between receive 
>> > and
>> > transmit, I use a spotting switch.  The spotting switch keys the PA 
>> > while
>> > simultaneously switching the output power from antenna to a dummy load.
>> > As
>> > long as the antenna is close to 50 ohms (which it is in my case because 
>> > I
>> > use a tuner), the spotting frequency is very close to the actual 
>> > transmit
>> > frequency.  The actual frequency shift in my setup is closer to 2.5KHz
>> > when
>> > fully loaded to 50W plate input (for 30W output) and that is far enough
>> > away
>> > from the receiver passband to make the backwave inaudible during 
>> > receive
>> > periods. Full voltage regulation of osc, PA screen and PA plate allows
>> the
>> > frequency pulling to take place so quickly this "chirp" is inaudible. 
>> > I
>> > have also asked a nearby ham to listen closely for the FM sidebands the
>> > pulling creates and these effects are also inaudible.  But what IS
>> audible
>> > are key clicks.   The clicks were cleaned up by simply using a little
>> > shaping on the high voltage keying transistor switch that interfaces my
>> > straight key or paddle to the PA cathode potential.  Finally, I needed
>> > some
>> > simple filtering of the power lines and keying line to keep harmonic
>> > energy
>> > within the box.  BTW these mods are not intrusive, are reversible, and
>> > were
>> > implemented on a rig that had already undergone the standard ham
>> > conversion
>> > by a previous owner.
>> >
>> > I have used this T-22 with a dipole on a regular basis over several 
>> > years
>> > for DX'ing and contesting as well as casual operation.  A foot-switch
>> > actuated T/R relay provides the rapid timing control needed for
>> contesting
>> > and chasing DX.  It was a lot of fun on 40M this past weekend during 
>> > the
>> > ARRL DX Contest.
>> >
>> > Dennis AE6C
>> >
>> >
>> > On Tue, Feb 23, 2010 at 1:10 AM, Henry Mei'l's <meils at get2net.dk> 
>> > wrote:
>> >
>> >> Dennis
>> >> Is your transmitting freq 2 kHz off your receiving freq.? -- How do 
>> >> you
>> >> adjust for the difference when you go from receive to transmit anf how
>> do
>> >> you know that your not sending a backwavce 2 kHz away from your 
>> >> key-down
>> >> freq. ?
>> >> Henry -OZ1UF
>> >>
>> >> ----- Original Message -----
>> >> From: "Dennis Monticelli" <dennis.monticelli at gmail.com>
>> >> To: "Discussion of AN/ARC-5 military radio equipment."
>> >> <arc5 at mailman.qth.net>
>> >> Sent: Tuesday, February 23, 2010 9:16 AM
>> >> Subject: Re: [ARC5] Fw: Model 19 MKll
>> >>
>> >>
>> >> > With my T-22 the continuously running oscillator (it runs during
>> >> > receive
>> >> > periods as well) does not create a backwave issue because the PA 
>> >> > pulls
>> >> the
>> >> > osc about 2KHz upon key down.  Regulation of all voltages eliminates
>> >> > chirp.
>> >> >
>> >> > Dennis AE6C
>> >> >
>> >> > On Mon, Feb 22, 2010 at 11:17 PM, Henry Mei'l's <meils at get2net.dk>
>> >> wrote:
>> >> >
>> >> >> Hi Meyer and everyone else
>> >> >> I used the method of running the a keying (T/R) relay in series 
>> >> >> with
>> >> >> the
>> >> >> 1625 cathodes of my ARC-5 xmtrs back in the 50's. It does gives you
>> >> >> cathode
>> >> >> bias-but you do lose some power because of the voltage drop,
>> depending
>> >> on
>> >> >> the relay coil resistance- I suppose you could have a pair of
>> contacts
>> >> >> that
>> >> >> short out the relay coil when it kicks in- wonder what that would 
>> >> >> do
>> >> >> to
>> >> >> the
>> >> >> signal (a kind of burp?).
>> >> >>
>> >> >> Of course, with the oscillator running, you wont be able to work 
>> >> >> QSK
>> >> >> and
>> >> >> you
>> >> >> probably will have a readable backwave -- I do when keying the
>> >> >> cathodes
>> >> >> of
>> >> >> my TCS final, with oscillator and multiplier stage unkeyed -- same
>> >> >> with
>> >> >> the
>> >> >> ARC-5's  I keyed that way.
>> >> >> You all are probably  aware of all this-- so call it nostalgia.
>> >> >>
>> >> >> 73s, Henry
>> >> >>
>> >> >> ----- Original Message -----
>> >> >> From: "Meyer Gottesman" <wrecktech at yahoo.com>
>> >> >> To: "Discussion of AN/ARC-5 military radio equipment."
>> >> >> <arc5 at mailman.qth.net>
>> >> >> Sent: Tuesday, February 23, 2010 12:52 AM
>> >> >> Subject: Re: [ARC5] Fw: Model 19 MKll
>> >> >>
>> >> >>
>> >> >> I stripped the usesless UHF out of my WS 19 also. The 80 and 40 CW
>> >> >> performance is FB. As said before, the only nasty element is the CW
>> >> >> keying
>> >> >> being at +275 volts. The R/T relay can become the 807 cathode
>> >> >> resistor.
>> >> >> If
>> >> >> the VFO runs all the time when transmitting and ONLY the 807 
>> >> >> cathode
>> >> >> is
>> >> >> keyed, there should be little or no chirp and I do not recall the
>> >> >> drift
>> >> >> being too bad.
>> >> >>
>> >> >> 73,
>> >> >>
>> >> >> Meyer Gottesman, W6GIV
>> >> >> Macon, GA
>> >> >>
>> >> >>
>> >> >>
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>> >> >>
>> >> >>
>> >>
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>> >> >> 08:34:00
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>>
>>
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