Hi Steve,

Thanks for the quick reply and the offer to help. I have a complete collection of the ER magazines (have had a subscription since ER#8) and enjoy it more than any magazine I receive. I will certainly look up your article and if it looks like I can manage to program one of these devices, I will certainly order several. I’m replacing crystals in a Beckman 905 receiver that receives WWV signals from 2.5-25mhz.

?

Thanks again,

Tom N5AMA

This package looks great and less expensive than ordering a crystal not to mention the reduced lead time. I opened the QRP Labs manual for this devise and had trouble with programming it for a specific frequency. It looks ideal to fit in a HC6/U but for a non computer savvy old timer, the programming of this devise to a specific frequency is a mystery.

My sickness concerning old vintage radios had morphed into revisiting
the CB radios I messed with when I was a young 'un.? I have noticed that
several have had one or more crystals out, which in a synthesized radio
one crystal is likely to take out 4 or more channels.? During my beating
on these old relics I decided to put a DDS signal generator across the
crystal, dial in it's frequency, and verify the "lost" channels were now
there and usable.? All worked as I expected except when I unhooked the
signal generator the channel was still functional!? Sometimes it would
stop working when I switched back and forth to a channel not on the
crystal, sometimes not.? The latest I tried was a Realistic TRC-47 which
is a 23 ch SSB rig and it had one crystal "dead."? I hooked up the SG
and brought the group of channels back to life and unhooked the SG.? All
channels were still alive and remained that way for the rest of the
day!? I'll see tomorrow if they still work when I turn it on.
Can someone explain this behavior?? It's almost like "goosing" the tired
crystal "repaired" it, or something.? After I get finished playing with
these old CBs I'm going to pull a Heathkit receiver off the shelf that
has a couple bad crystals and see if it will wake them up.
73,
--
Justin B.
KI5GKD

On 03/10/2025 2:23 PM PDT Jim Whartenby via groups.io <old_radio@...> wrote:

?

?

Tom

The two original paper caps in the LO compartment are the ones that you say are still there and need to be replaced?

?

What C# are they?

Jim

?

Logic: Method used to arrive at the wrong conclusion, with confidence.? Murphy

?

?

On Sunday, March 9, 2025 at 12:11:11 PM CDT, Allthumbs via groups.io <btse1@...> wrote:

?

?

Don, here's a photo of the underside in its as-found state. Not too bad but not something a sane person would plug in and turn on without at least replacing the electrolytics. Obviously it had seen some repairs over the years. I have since replaced most resistors and capacitors and replaced the old 2-wire power cord with a modern 3-wire.

?

Tom

?

On 03/08/2025 5:06 PM PST don Root <drootofallevil@...> wrote:

?

?

Tom, did you mention what state it was in when you got it.. as to the components around the 6K8 . original looking? … or otherwise? ??Any mucking by somebody could have moved a connection…. and…so!

?

?

?

--
don??? va3drl

?

On 03/08/2025 5:06 PM PST don Root <drootofallevil@...> wrote:

?

?

Tom, did you mention what state it was in when you got it.. as to the components around the 6K8 . original looking? … or otherwise? ??Any mucking by somebody could have moved a connection…. and…so!

?

?

?

--
don??? va3drl

?

?

Justin:

?

I didn't recognize your name in my initial response. I indicated I just finished a manual for a HE-43C. When I was putting the mailing label on the envelope, I realized it was for you. So it's on the way. Ah; the perils of aging.

?

Pete, wa2cwa

?

----- Forwarded Message -----

Date: Sat, 8 Mar 2025 12:49:44 -0500

Subject: Re: [HallicraftersRadios] Off-The-Wall Question

?

Lafayette HE-43C is not rare. It is identical to the HE-20C (which we sold 1000's of these sets - HE-20, 20A, 20B, 20C(relay and electronic switching versions), 43C) except the 43C works on 110V AC and 6 volts DC. The 20C works on 110V AC and 12 volts DC. Other then that, they are identical. I just finished a HE-43C manual for a customer. Both the HE-20C and 43C were made by United Scientific Laboratories (USL) in Long Island City, NY.

A tunable receive and a crystal controlled transmitter was quite common with a number of manufacturers in the early 60's. A Spot switch obviously was common on these transceivers.

?

Pete, wa2cwa

?

?

On Sat, 08 Mar 2025 08:46:48 -0800 "Justin Bowser - KI5GKD" <justin.bowser@...> writes:

Pete - I'll give that a try and let you know.? I also got another rare/unusual bird coming, an HE-43C.? I've never seen a CB where you transmit with crystal and receive by VFO.? What I plan doing is to put in a circuit that replaces the crystals with an Arduino controlled 5351 module.

?

73,

Justin B.
KI5GKD

_._,_._,

On 03/08/2025 3:26 PM PST Jim Whartenby via groups.io <old_radio@...> wrote:

?

?

Tom

The following is excerpted from QST, February, 1941

?

"The high oscillator transconductances of the 6K8 and 6SA7 make them particularly suited for all-around usage. They oscillate strongly at high frequencies where L/C ratios are unfavorable. The 6A8 construction is not satisfactory for amateur usage because of instability in the oscillator. The oscillator electrode is a pair of rods located in the tube between the No. 1 grid and the screen.

These side rods collect electrons from the cathode stream and the electrode current is controlled by the No. 1 grid. Unfortunately, changes in signal-grid or screen voltage also change the anode current. This conductance between signal grid and oscillator causes instability with variation in a.v.c. voltage. Fluctuations in screen voltage due to supply regulation also change the frequency ... skip...

The 6K8 has been used extensively by the amateur and also the commercial manufacturer principally because it gives fair stability, and design problems are usually simple. The tuned-grid oscillator shown in Fig. 5 gives very little trouble and is easy to build.?The oscillator frequency is not independent of screen and a.v.c. voltages, but in most designs the frequency shift caused by one is offset by the other so that good stability is obtained. The 6K8 has an effect known as space-charge coupling which is experienced at high frequencies. This effect is as follows: The oscillator voltage on the No. 1 grid causes a fluctuation in the number of electrons in the region of the signal grid. The electron density changes at the oscillator frequency and as a result a displacement current flows into the signal grid. At high frequencies where the signal grid and oscillator frequencies are quite close, the impedance of the signal grid circuit at the oscillator frequency is quite high and as a result the displacement current produces an a.o. voltage across the signal grid circuit. This voltage, when smaller than the bias, reduces the gain of the tube slightly. Under extreme conditions it overrides the bias and causes rectification in the signal-grid circuit, causing a serious loss in gain. The coupling can be neutralized by a small capacitance - approximately 2 or 3 ??f d. - between oscillator and signal grids. Commercial practice is to use a condenser (known as a "gimmick") made by wrapping two pieces of wire together to give the desired capacitance. Neutralizing the space charge increases the gain and image ratio."

?

The bold print above is my doing.? Perhaps a little attention should be given to other tube sections.? ?In your tube pin measurements, shown below, you do not measure the grid cap voltage.? If C5 is leaking then the 6K8 control grid will be positive which will have an affect on the triode oscillator section of 6K8 because of the common cathode.

Just a thought,

Jim

Logic: Method used to arrive at the wrong conclusion, with confidence.? Murphy

?

?

On Tuesday, March 4, 2025 at 02:41:02 PM CST, Allthumbs via groups.io <btse1@...> wrote:

?

?

Newish member of this group, first time posting. I have an S-20R in need of repair. I am not a trained technician and am not particularly good at interpreting symptoms. However, I do have the chassis working just as it should from the grid of the first i.f. through the audio output. But the mixer stage is faulty—the LO is not oscillating.

?

I have a voltage chart for an S-20R that was made up by a member of the Antique Radio Forum. The tube pin voltage readings on my chassis agree almost entirely with his chart, except for the 6K8 mixer. I’m posting the readings in the chart below. FYI—I took these readings with the chassis powered via a bucking transformer so that it runs on 117 vac. On the first line are his readings and on the second line, in red, are my own. FWIW, my voltage readings were made with a DMM, not a VTVM.

?

?

If it helps, here's the mixer section:

If you’re familiar with these sets, you might recall that the underside of the 6K8 socket is a bit difficult to access because the oscillator coil assembly partially covers it. Maybe the symptoms I’m posting will point to a solution that would mean I won’t face the daunting task of partially disconnecting and ?lifting the whole coil assembly.? :-)

?

Any thoughts? Thank you,

?

Tom

On 03/08/2025 5:06 PM PST don Root <drootofallevil@...> wrote:

?

?

Tom, did you mention what state it was in when you got it.. as to the components around the 6K8 . original looking? … or otherwise? ??Any mucking by somebody could have moved a connection…. and…so!

?

?

?

--
don??? va3drl

On 03/08/2025 3:26 PM PST Jim Whartenby via groups.io <old_radio@...> wrote:

?

?

Tom

The following is excerpted from QST, February, 1941

?

"The high oscillator transconductances of the 6K8 and 6SA7 make them particularly suited for all-around usage. They oscillate strongly at high frequencies where L/C ratios are unfavorable. The 6A8 construction is not satisfactory for amateur usage because of instability in the oscillator. The oscillator electrode is a pair of rods located in the tube between the No. 1 grid and the screen.

These side rods collect electrons from the cathode stream and the electrode current is controlled by the No. 1 grid. Unfortunately, changes in signal-grid or screen voltage also change the anode current. This conductance between signal grid and oscillator causes instability with variation in a.v.c. voltage. Fluctuations in screen voltage due to supply regulation also change the frequency ... skip...

The 6K8 has been used extensively by the amateur and also the commercial manufacturer principally because it gives fair stability, and design problems are usually simple. The tuned-grid oscillator shown in Fig. 5 gives very little trouble and is easy to build.?The oscillator frequency is not independent of screen and a.v.c. voltages, but in most designs the frequency shift caused by one is offset by the other so that good stability is obtained. The 6K8 has an effect known as space-charge coupling which is experienced at high frequencies. This effect is as follows: The oscillator voltage on the No. 1 grid causes a fluctuation in the number of electrons in the region of the signal grid. The electron density changes at the oscillator frequency and as a result a displacement current flows into the signal grid. At high frequencies where the signal grid and oscillator frequencies are quite close, the impedance of the signal grid circuit at the oscillator frequency is quite high and as a result the displacement current produces an a.o. voltage across the signal grid circuit. This voltage, when smaller than the bias, reduces the gain of the tube slightly. Under extreme conditions it overrides the bias and causes rectification in the signal-grid circuit, causing a serious loss in gain. The coupling can be neutralized by a small capacitance - approximately 2 or 3 ??f d. - between oscillator and signal grids. Commercial practice is to use a condenser (known as a "gimmick") made by wrapping two pieces of wire together to give the desired capacitance. Neutralizing the space charge increases the gain and image ratio."

?

The bold print above is my doing.? Perhaps a little attention should be given to other tube sections.? ?In your tube pin measurements, shown below, you do not measure the grid cap voltage.? If C5 is leaking then the 6K8 control grid will be positive which will have an affect on the triode oscillator section of 6K8 because of the common cathode.

Just a thought,

Jim

Logic: Method used to arrive at the wrong conclusion, with confidence.? Murphy

?

?

On Tuesday, March 4, 2025 at 02:41:02 PM CST, Allthumbs via groups.io <btse1@...> wrote:

?

?

Newish member of this group, first time posting. I have an S-20R in need of repair. I am not a trained technician and am not particularly good at interpreting symptoms. However, I do have the chassis working just as it should from the grid of the first i.f. through the audio output. But the mixer stage is faulty—the LO is not oscillating.

?

I have a voltage chart for an S-20R that was made up by a member of the Antique Radio Forum. The tube pin voltage readings on my chassis agree almost entirely with his chart, except for the 6K8 mixer. I’m posting the readings in the chart below. FYI—I took these readings with the chassis powered via a bucking transformer so that it runs on 117 vac. On the first line are his readings and on the second line, in red, are my own. FWIW, my voltage readings were made with a DMM, not a VTVM.

?

?

If it helps, here's the mixer section:

If you’re familiar with these sets, you might recall that the underside of the 6K8 socket is a bit difficult to access because the oscillator coil assembly partially covers it. Maybe the symptoms I’m posting will point to a solution that would mean I won’t face the daunting task of partially disconnecting and ?lifting the whole coil assembly.? :-)

?

Any thoughts? Thank you,

?

Tom