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THE AM BULLETIN BOARD => Technical Forum => Topic started by: W7BID on November 18, 2022, 10:34:35 AM



Title: 6 meter rig
Post by: W7BID on November 18, 2022, 10:34:35 AM
r r r

Hi from ID.

My first 6m rig, now to get it running.

Estate sale, before I plug it in (and blow a fuse) has anyone seen anything like this? Not all knobs are marked but a little research has given my the courage to fire it up.

The single jack in rear is microphone? Ceramic or ?

Your thoughts and comments appreciated.
W7BID


Title: Re: 6 meter rig
Post by: KD1SH on November 18, 2022, 11:37:16 AM
  That is a very nifty little 6 meter rig. Nice find. No manufacturer's name or model visible in the pictures; could be home-brew, with some very nice workmanship. Hard to get size in perspective in the picture - are those tubes 6146's or 2E26's? I'm thinking they're probably the latter. The Jones plug on the rear panel would be for the power supply; there are no internal power supply components visible. Do you have the power supply?
   The meter has "Arrow" on it, but that could be the maker of the meter. The only reference I find to an Arrow ham rig is to an 80 meter novice CW rig built back in the 50's, but this is clearly a 6 meter rig.
   If you don't have the power supply, and no schematic, you'll have to do some reverse-engineering: trace out the circuitry; make your own schematic, and then build your own power supply for it, as well as a modulator if you want to use it on AM (unless it's screen modulated).
   There is no modulation transformer visible either, so either it's screen modulated or it's a CW rig, or the modulator is built into the power supply. The phono-jack on the rear panel is probably for a key if it's a CW rig. Take a close look at that phono-jack - does it have three terminal contacts? If it does, then it might indeed be a microphone connector, with one contact being for the PTT, one for ground, and the other for the audio.
      There's a crystal jack on the front panel, but also a VFO. Does one of the front panel controls - I can't read any labeling on two of them - switch from VFO to Crystal? The meter has increments for S-units, so maybe it's a transceiver and the VFO is for receive only - many old 6 meter rigs were like that. If it's a transceiver, where is the speaker? Maybe it's supposed to be in the power supply, as in the Gonset G-76.
   Also, I wouldn't be in a hurry to power it up - old electrolytic caps are often very degraded with age and disuse. I would recap an old rig like that before powering it up, or at the very least, power it up very slowly and gradually, over several hours, with a variac, and don't leave it unattended during the process; in a worst-case scenario old electrolytics can explode and catch fire.
   You've got a cool old radio there, but I'd look at it as a project rather than a ready-to-play rig. Good luck with it.

Edit: looking again at the picture, I see what might be a small transformer right above the Jones plug. Might be a modulation transformer - it doesn't look big enough to power the rig, so I'm still thinking the power supply is external.


Title: Re: 6 meter rig
Post by: w8khk on November 18, 2022, 12:20:15 PM
In addition to Bill's (KD1SH) comments, my observation is that the rig looks like it is definitely a homebrew, based upon the metalwork.  The receiver front-end is built as a subassembly, and the opening in the main chassis has drill holes in the corners; it looks like it was cut out manually, not mass-produced.  (Maybe the sub-chassis is an update to a previous configuration, where the original chassis holes did not comply with the desired changes?)  The planning and assembly indicates a great deal of experience and attention to detail.  The layout and workmanship is well above average homebrew!  Notice the sub-chassis lowering the final tubes to fit in the small enclosure, and the careful winding and placement of the coils, and neutralizing stubs.

The transmitter section looks like the standard crystal oscillator, multiplier(s) and a tuned driver stage to a pair of neutralized push-pull 6146s, with link-coupled output.  Looking at the wiring, there is no evidence of any ability to use the tuning dial as a transmitter VFO.

The receiver looks to be a standard superhet, with an RF amplifier, gang-tuned oscillator and mixer, and several IF stages. It should be relatively easy to trace the schematic, stage-by-stage. 

It might be interesting to start by tracing the wires to the rotary switch at the bottom center, to determine what the various functions may be.  Once the main schematic is completed, it should be relatively obvious as to what is needed for a power supply and possibly a modulator.  Maybe the receive audio amplifier was part of the power supply?  What is the knob just under the meter?

The 1/4" jack on the back of the chassis has tip, ring, and sleeve, and there is a T/R relay in the corner; these features indicate it may have been an AM rig.  The size and form factor would lead me to believe it was once under the dash of a motor vehicle.  Too bad the two mystery knobs have no labels. 

What is the pot on the left side of the chassis?  Perhaps a squelch control?

Please share answers to these questions as you further analyze the rig!


Title: Re: 6 meter rig
Post by: Carl WA1KPD on November 18, 2022, 06:27:35 PM
By elimination, I would bet that the knob under the meter is volume.
Neat little rig.


Title: Re: 6 meter rig
Post by: Pete, WA2CWA on November 18, 2022, 07:34:20 PM
Here's a thread on the same mystery 6 meter transceiver that was posted on the Antique Radio forum. It can save you for posting information and/or asking questions that's already been posted and/or discussed.
https://antiqueradios.com/forums/viewtopic.php?f=5&t=419685


Title: Re: 6 meter rig
Post by: KD1SH on November 18, 2022, 08:20:55 PM
  Excellent, Pete - thanks for posting that. If those two rigs are home-brew, they were built by the same builder, but more likely it was a small commercial builder; the physical layout is just too identical. Or maybe they were prototypes that never made it to production?
   It also seems that the OP does have the matching power supply, which is good news. Way too often we find rigs - the Clegg Zeus and Gonset G-76 come to mind - that are missing their power supplies. The original owner passes away, and when his stuff gets sold the power supplies often go into a dumpster because the non-hams involved don't recognize them for what they are. They're just big, heavy, clunky looking metal boxes that don't look like something anyone would want, so off to the dumpster they go.
   I hope the OP continues to post his progress with this.


Here's a thread on the same mystery 6 meter transceiver that was posted on the Antique Radio forum. It can save you for posting information and/or asking questions that's already been posted and/or discussed.
https://antiqueradios.com/forums/viewtopic.php?f=5&t=419685


Title: Re: 6 meter rig
Post by: W7BID on November 18, 2022, 08:46:28 PM
Yes, thanks Pete..although that thread contained later adding this unit it originally focused on another rig.

Here is the assumed power supply. The switches are marked ‘hv’, 12vac and far right is unmarked.

There are two wires coming from plug that best guess would be for a speaker since in the rig the volume pot runs to the plug.

I really appreciate the discussion as I am less knowledgable about rigs as old as I am.

👍
W7bid


Title: Re: 6 meter rig
Post by: Pete, WA2CWA on November 19, 2022, 02:42:06 AM
Look at the underside of the "transceiver" wiring
Look at the underside wiring of the power supply
Hard to believe they were done by the same person  ::)

Look at the date codes on some of the capacitors to get a rough idea of their manufacture date. Would give you a rough idea of the time frame of overall construction to some degree.

Problem is that back in the late 50's through the 60's there were a lot of VHF construction articles that appeared in a number of mainstream magazines and publications. There were also a number of small time VHF monthly publications that popped up during this time frame. QST, CQ, and early 73 magazines had VHF articles. ARRL Handbook, The Radio Handbook

If you go here: https://worldradiohistory.com/Short_Wave_Miscellaneous.htm
and scroll down to Television & UHF DX and Reception you'll find a number of small time VHF publications that had construction articles during the late 50's/early 60's time frame. Maybe you'll get lucky.

I suspect the receiver must really suck. No RF gain control, no AVC. If that lowest control nearest the VFO/tuning knob is a 3 position switch, why would you label one position "zero"?

If one could overlay actual tube numbers on the top view picture, some one with a "creative" mind could possibly come up with a possible block diagram.

One could review the power supply connector pins and see if they make sense mating up with the connector pins in the transceiver.

Or, we can just stare at the pictures and ...


Title: Re: 6 meter rig
Post by: KF4NU on November 21, 2022, 05:52:03 PM
If one position of the 3 position switch is marked "ZERO", that for zero beating the receiver to the transmitter.  The other 2 positions are either AVC On and Off, or a fixed BFO On and Off.  It's a cool looking rig.


Title: Re: 6 meter rig
Post by: Pete, WA2CWA on November 21, 2022, 06:36:44 PM
If one position of the 3 position switch is marked "ZERO", that for zero beating the receiver to the transmitter.  The other 2 positions are either AVC On and Off, or a fixed BFO On and Off.  It's a cool looking rig.

I guess you didn't review the link I provided very closely which also shows mystery rig #2 which evidently was constructed using the same plans. Pictures were also included.
SEE closeup of front panel from mystery rig #2 "3 position"? switch markings below:


Title: Re: 6 meter rig
Post by: WA2SQQ on November 23, 2022, 07:51:17 AM
Run the photo through the Google photo app and see if it finds anything.
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