Hy-gain / Hy-range "V" M# 674b and Hy-range VI VFO M# 675

[kc]

Hello to all,

This is my first post, So I will try hard not to seem to stupid, I have always like Radio Communications since my first set of Walkie-Talkies,

And now that I have been forced into retirement against my will, I would like to start this hobby again!  I passed my Tech license a couple of years ago, But I never set a station up, So.... Its time!   I set my 11 meter up first, 10 meter 2nd, and I am working on 6 meter next, Its all old equipment I already had, But most of it works, And its keeping me occupoed, Out of trouble, and at home where the Warden (wife) can keep an eye on me. 

So to the question, The warden coerced me into going to a Flea market with her a few weeks ago, Once there, I was able to give her the slip for about 20 minutes, In that time I found an Old 23 channel Hy-gain, Being from Nebraska I immediately took an interest in this radio, The price was right, $10.00 sold!

The ID tags are completely missing, And the only means of Identification are from the Internet, So I am looking for Schematics, Operating Manual, Any info on how to setup, Calibrate the VFO and Antenna Tune and Load, Basically , How do I use this radio correctly?

I have read some post here on Grumpy's, But I could not find any specifics, This is a really interesting radio, And its reception is far better than my stock Uniden Washington,   It does turn on , It keys up, but with weak audio, I think it has Microphone issue, possibly bad cord,  Other than that I am not sure. I am including  a couple of pics for reference, Thanks for any help. 73's 

 

[Sandbagger]

Jan 28, 2017 19:08:10 GMT -5 kc said:

Hello to all,

This is my first post, So I will try hard not to seem to stupid, I have always like Radio Communications since myView AttachmentView Attachment first set of Walkie-Talkies,

And now that I have been forced into retirement against my will, I would like to start this hobby again!  I passed my Tech license a couple of years ago, But I never set a station up, So.... Its time!   I set my 11 meter up first, 10 meter 2nd, and I am working on 6 meter next, Its all old equipment I already had, But most of it works, And its keeping me occupoed, Out of trouble, and at home where the Warden (wife) can keep an eye on me. 

So to the question, The warden coerced me into going to a Flea market with her a few weeks ago, Once there, I was able to give her the slip for about 20 minutes, In that time I found an Old 23 channel Hy-gain, Being from Nebraska I immediately took an interest in this radio, The price was right, $10.00 sold!

The ID tags are completely missing, And the only means of Identification are from the Internet, So I am looking for Schematics, Operating Manual, Any info on how to setup, Calibrate the VFO and Antenna Tune and Load, Basically , How do I use this radio correctly?

I have read some post here on Grumpy's, But I could not find any specifics, This is a really interesting radio, And its reception is far better than my stock Uniden Washington,   It does turn on , It keys up, but with weak audio, I think it has Microphone issue, possibly bad cord,  Other than that I am not sure. I am including  a couple of pics for reference, Thanks for any help. 73's 

 

First off, I want to say welcome to the forum. We specialize in "old time" CB radios, using them and restoring them, and talking about them.

Now on to your questions. I'm a little confused, as I'm sure it's a simple mistake, but The Hy-Gain Hy-Range 5 was offered as two versions, the 674a with the bat handle toggle switches that light up on the tip is the version that had the VFO jack on the back, while the updated model, the 674b, had push button switches and no VFO jack. Anyway, I could not locate the 674a schematic, but I did locate the 674b. I don't recall if they are the same circuitry inside and the only changes were cosmetic, or not. But if it helps, here it is:

www.cbtricks.com/radios/hygain/hyrange_5_674b/index.htm

I could not find the schematic for the VFO, so hopefully that's still working. That was quite the setup back in the day. Of course you couldn't legally transmit with a VFO, so Hy-Gain set it up so that it only worked on receive out of the box. But it was a simple modification to enable transmit on the VFO as well. Evidently the FCC frowned on this, and Hy-Gain dropped the VFO from their lineup and "b" model radios without the VFO jack took the place of the models that used to have it. So that is a somewhat collectable setup you have there. The "a" version is somewhat rare. There were a lot more "b' versions made.

[kc]

Thank-You Sandbagger for replying, I am confused too. You wrote: "The Hy-Gain Hy-Range 5 was offered as two versions, the 674a with the bat handle toggle switches that light up on the tip is the version that had the VFO jack on the back, while the updated model, the 674b, had push button switches and no VFO jack."    I wonder if I have an Export version or just a weird variant? Because I have the push buttons upfront, But,  On the back it has a TVI adjustment, Antenna Tune adjustment, Antenna Load adjustment, Receiver jack, and the VFO jack, All stamped/ labeled into the chassis.  My main concern is setting this Rig up properly, The VFO has a calibrate button on it, But I don't know the proper procedure to calibrate,   And my guess is there is a SOP in a manual, Or in somebodies memory banks that explains all.
The front of my the radio looks like this, With push buttons:  
 
 

While the back of my the radio looks like this, With the VFO jack:

And the back of the  radio M#674-B listed at cbtricks.com looks like this:

[kc]

It looks like there are 3 variants of this radio, 1. M#674 , 2. M#674a , 3. M#674b

Also 2 variants of the VFO , 1. M#675 , 2. M#675a

I ordered the SAMS #70 for the radio variants 674 / 674a

I also ordered the SAMS #64 for both variants of the VFO 675 / 675a

Both were on E-bay, very reasonable,They should be here next week, And I would be glad to Scan and Share with anyone interested.

Any info regarding this Radio and VFO would still be greatly appreciated.

Thanks again!!   73's

[kc]

So far these are  the most details I can find out about these radio's , I can't wait to get the SAM's I ordered !!  This will be a fun project. 73    kc

Credit to: CB DAZE: October 2009 A continuation of Woody's 'Nuff Said column from the CBGAZETTE website

Hello Woody,
I thought you might want to know that some of the information on your Hy-Gain V review page at www.cbgazette.com/rev_hygainv.html is not correct. The 674A that you have photos of on that page is definitely NOT a stock configuration - the lighted toggle switches are a modification added by someone. The 674 and 674A had the same push buttons as the 674B. The 674 had the VFO socket on the back, as pictured; the 674A was the same internally as the 674, but the VFO socket and wiring was left out. There was either an empty hole or a blank panel, depending on the vintage of the 674A. A wiring harness and instructions was included with later model 675A VFOs so they could be added to the 674A (and other 6xxA models, excepting of course 623A)that did not include the socket.
Another way to tell the difference between the 674/A and the 674B is the 674/A models used a 4-pin mic jack; the 674B a 5-pin DIN. There is also an access hole on the back of the 674/A models for adjustment of the "Load" capacitor. This hole is absent on the 674B. The speaker grille is also in a different location, being on the side of the 674/A and the bottom of the 674B. There are other subtle differences in the outer case design, but these are the big ones. From the pic on your page, the model shown is quite definitely a 674, as is shown clearly by the model tag. The 674A would be labeled as such, and did not have the VFO socket screwed to the chassis.
I live in Lincoln, Nebraska, and work in the former Hy-Gain plant. I've seen many of the various flavors of 674 over the years (although I did not work at Hy-Gain in those days). You are correct in that it is the easiest 10-Meter conversion ever - I have a 674A/675A that I put on 10meters many years ago, and currently another one on the bench for a friend undergoing the same conversion. A point of trivia, the 675A VFO can be connected to the 674B - if you know what you are doing. It requires adding an 11.272 crystal in the carrier oscillator circuit, some re-wiring of the synthesizer switching around the mode switch, and the 674B MUST have a black-label crystal filter. The later versions used a silver labeled crystal filter that was broader (compromise for AM operation) and does not work as well. I did one of these years ago, and it's probably still floating around here somewhere. It may be the only one in the country, AFAIK. These days, it's not worth the effort, of course. But it can be done. Jim.

Again Thank-You Woody and Jim !

[Sandbagger]

Jan 29, 2017 9:04:34 GMT -5 kc said:

So far these are  the most details I can find out about these radio's , I can't wait to get the SAM's I ordered !!  This will be a fun project. 73    kc

Credit to: CB DAZE: October 2009 A continuation of Woody's 'Nuff Said column from the CBGAZETTE website

Hello Woody,
I thought you might want to know that some of the information on your Hy-Gain V review page at www.cbgazette.com/rev_hygainv.html is not correct. The 674A that you have photos of on that page is definitely NOT a stock configuration - the lighted toggle switches are a modification added by someone. The 674 and 674A had the same push buttons as the 674B. The 674 had the VFO socket on the back, as pictured; the 674A was the same internally as the 674, but the VFO socket and wiring was left out. There was either an empty hole or a blank panel, depending on the vintage of the 674A. A wiring harness and instructions was included with later model 675A VFOs so they could be added to the 674A (and other 6xxA models, excepting of course 623A)that did not include the socket.
Another way to tell the difference between the 674/A and the 674B is the 674/A models used a 4-pin mic jack; the 674B a 5-pin DIN. There is also an access hole on the back of the 674/A models for adjustment of the "Load" capacitor. This hole is absent on the 674B. The speaker grille is also in a different location, being on the side of the 674/A and the bottom of the 674B. There are other subtle differences in the outer case design, but these are the big ones. From the pic on your page, the model shown is quite definitely a 674, as is shown clearly by the model tag. The 674A would be labeled as such, and did not have the VFO socket screwed to the chassis.
I live in Lincoln, Nebraska, and work in the former Hy-Gain plant. I've seen many of the various flavors of 674 over the years (although I did not work at Hy-Gain in those days). You are correct in that it is the easiest 10-Meter conversion ever - I have a 674A/675A that I put on 10meters many years ago, and currently another one on the bench for a friend undergoing the same conversion. A point of trivia, the 675A VFO can be connected to the 674B - if you know what you are doing. It requires adding an 11.272 crystal in the carrier oscillator circuit, some re-wiring of the synthesizer switching around the mode switch, and the 674B MUST have a black-label crystal filter. The later versions used a silver labeled crystal filter that was broader (compromise for AM operation) and does not work as well. I did one of these years ago, and it's probably still floating around here somewhere. It may be the only one in the country, AFAIK. These days, it's not worth the effort, of course. But it can be done. Jim.

Again Thank-You Woody and Jim !

Well, that explains some of my confusion, as Woody and I had been pretty good friends for a while (He seems to have disappeared from the internet as of late and doesn't seem to be active on the radio circuits. Hope he's ok), and we shared much information about vintage radios. It was his site that showed the 674A with the bat handled toggle switches, and I (erroneously evidently) believed that that was the stock configuration for the "A" version. I've only ever seen one of the older 674's with the VFO on it, and that was back in 1975, so my recollection of it was foggy. All the others were newer versions without the VFO jack. Based on the knob layout and meter placement, I always suspected that the older 674 and the Lafayette Telsat SSB-50 were twins. The schematic for the 674B though, shows an updated circuit, which more closely resembles the Midland 13-898B, so I'm guessing that they made major circuit changes when they went from the "A" to the "B" versions.

As to your question about the calibrate function, it's probably not all that complicated. There's probably a specific channel that you spot tune to with the channel selector, and you adjust the calibrate knob so that the frequency dial on the VFO agrees with the channel. Of course that assumes that the crystals are on-freq......

[Trapper_267]

Very interesting thread here.
I have a 674B and the 675A. 
Nice info on the models as well and i also have the Sams photofact vol's 64 and 70, Still looking for vol. 129 for the 674BHere's my set up

[Trapper_267]

Here's alittle some thing i borrowed from Fred Storms off Face Book

Here is his Hy-Range 6, Hy-Gain 5 and Hy-range 5.

Note that the Hy-Range 5 and Hy-Gain 5 look the same but named different. Anyone ever seen this?

[Sandbagger]

Feb 5, 2017 2:34:49 GMT -5 Trapper_267 said:

Here's alittle some thing i borrowed from Fred Storms off Face Book

Here is his Hy-Range 6, Hy-Gain 5 and Hy-range 5.

Note that the Hy-Range 5 and Hy-Gain 5 look the same but named different. Anyone ever seen this?






View Attachment

I suspect this is also a different "version", although I think the differences are mostly cosmetic at this point. Notice that the older 674A has the PA function on the channel selector, while the 674B and the "Hy-Gain V" have the PA function on the squelch, which would suggest that the Hy-Gain V came after the 674A, and most likely the 674B as well.

I enjoy these threads where we track the evolution of certain radio models. Often the only information we have is anecdotal. But with enough evidence we can usually piece together a timeline.

[doctor]

Interesting about HY-GAIN.
I remember back in 1980 that I had a hygain, cannot remember the model, plain unit off/on/squelch channel changer mic plug. It was converted to ten meters fm , some chap did them for $25 each, worked very good, don't remember what happen to it.

The wireman use to convert cb radios to 10 fm, he did over a thousand if I remember right.
Enough rambling.
DOCTOR/795

[Sandbagger]

Feb 6, 2017 11:36:24 GMT -5 doctor said:

Interesting about HY-GAIN.
I remember back in 1980 that I had a hygain, cannot remember the model, plain unit off/on/squelch channel changer mic plug. It was converted to ten meters fm , some chap did them for $25 each, worked very good, don't remember what happen to it.

The wireman use to convert cb radios to 10 fm, he did over a thousand if I remember right.
Enough rambling.
DOCTOR/795

It's very easy to convert early 40 channel PLL radios (like the Cybernet PLL02a Hy-Gain radios) to 10 meters. Most of them can be done without even changing crystals. Just a realignment and reprogramming of the PLL control pins. Adding FM is just a matter of installing a FM discriminator/detector chip (they have single chip versions that work well) for the receiver and adding a bit of TX audio to the PLL VCO.

[nailerdog]

Brings back memories from 1976. I had a Hygain V and VI that was connect to a Palomar 100 watt unit. Antenna was a 102 stainless whip.

Talked all over the country with that little unit when skip was rolling. Moved from the Hygain gear to a SBE Sidebander with a Siltronix VFO that was a little more refined from the VFO perspective. It looked really mean on the center hump of my 64 Chevelle SS convertible.

[Trapper_267]

Feb 5, 2017 2:34:49 GMT -5 Trapper_267 said:

Here's alittle some thing i borrowed from Fred Storms off Face Book

Here is his Hy-Range 6, Hy-Gain 5 and Hy-range 5.

Note that the Hy-Range 5 and Hy-Gain 5 look the same but named different. Anyone ever seen this?

I contacted Fred about his Hy-Gain 5 that look's like a Hy-Range 5 and he said it was made in  Purto Rico, not Lincoln, NE.

[2600]

Hy-Gain's 23-channel radios were made in Japan by Cybernet, who supplied many other brands as well. Hy-Gain was in Nebraska, but the radios were made in Japan. Think "Lafayette". They were on Long Island, but never made a radio, just hired a factory to put their name tag on it.

Around 1976 Hy-Gain decided to buck the trend. The Japanese Yen surged upwards in value, as the trade value of the dollar fell directly in step with the rising price of crude oil at the time. Japanese labor and japanese products bought with dollars began to cost more and more. Suddenly importing from Japan wasn't so cheap as it had been. Hy-Gain made the courageous decision to 'sorta' make stuff in the USA. They licensed Cybernet's radio designs and tooled up a factory in Puerto Rico, the cheapest USA labor market, where no import fees or currency-exchange rates would affect the cost to build radios. And the exchange rate of the Yen was not so big a liability. Parts still came from Japan, but they're cheaper.

And then the 40-channel expansion from 23 channels totally crashed the market for a CB radio. Nobody would buy a 23-channel radio when the 40-channel stuff was "just around the corner". The loans taken out by CB brand names to build radios came due and a few brands went under with no sales to pay their bills. The FCC sat on their hands a long time coming up with new rules before any 40-channel radios could be approved for legal "Type-Accepted" sale. By the time you could actually buy a 40-channel nobody would. By then the oversupply of 23-channel radios was being dumped at pennies on the dollar by way of bankruptcy sales.

As a result, 40-channel radios began to flood the market by way of bankruptcy sales as folks who mortgaged the farm to build new "40s" began to go under by the dozen. By the early 80s this left only Midland, Cobra, RatShack and President/Uniden. The other hundred-plus brands were all history.

Hy-Gain's Puerto Rico experiment was the last CB made inside a USA border. Factory closed, and leftover Hy-Gain circuit boards/chassis were seen in surplus-electronics catalogs for decades after. Seems to me that John Boy was still selling some of these on Ebay from old Maco stock.

"I'm from the government and I'm here to help".

73

[Sandbagger]

Mar 5, 2017 1:36:37 GMT -5 2600 said:

Hy-Gain's 23-channel radios were made in Japan by Cybernet, who supplied many other brands as well. Hy-Gain was in Nebraska, but the radios were made in Japan. Think "Lafayette". They were on Long Island, but never made a radio, just hired a factory to put their name tag on it.

Around 1976 Hy-Gain decided to buck the trend. The Japanese Yen surged upwards in value, as the trade value of the dollar fell directly in step with the rising price of crude oil at the time. Japanese labor and japanese products bought with dollars began to cost more and more. Suddenly importing from Japan wasn't so cheap as it had been. Hy-Gain made the courageous decision to 'sorta' make stuff in the USA. They licensed Cybernet's radio designs and tooled up a factory in Puerto Rico, the cheapest USA labor market, where no import fees or currency-exchange rates would affect the cost to build radios. And the exchange rate of the Yen was not so big a liability. Parts still came from Japan, but they're cheaper.

And then the 40-channel expansion from 23 channels totally crashed the market for a CB radio. Nobody would buy a 23-channel radio when the 40-channel stuff was "just around the corner". The loans taken out by CB brand names to build radios came due and a few brands went under with no sales to pay their bills. The FCC sat on their hands a long time coming up with new rules before any 40-channel radios could be approved for legal "Type-Accepted" sale. By the time you could actually buy a 40-channel nobody would. By then the oversupply of 23-channel radios was being dumped at pennies on the dollar by way of bankruptcy sales.

As a result, 40-channel radios began to flood the market by way of bankruptcy sales as folks who mortgaged the farm to build new "40s" began to go under by the dozen. By the early 80s this left only Midland, Cobra, RatShack and President/Uniden. The other hundred-plus brands were all history.

Hy-Gain's Puerto Rico experiment was the last CB made inside a USA border. Factory closed, and leftover Hy-Gain circuit boards/chassis were seen in surplus-electronics catalogs for decades after. Seems to me that John Boy was still selling some of these on Ebay from old Maco stock.

"I'm from the government and I'm here to help".

73

It was an interesting time for operators. Not so much for manufacturers. I knew several locals who bought Lafayette Telsat 50a's for $49 in 1978, as Lafayette was purging their leftover stock. And somehow Radio Shack became the liquidator for Johnson 4740's, which was a fairly decent 40 channel SSB rig, which closed out for $99. And when the 80's rolled around, the prices for CB radios dropped considerably. In the 70's you couldn't touch a SSB mobile rig for under $260. In the 80's you could get one for $100 cheaper. A whole lot of cheap and dirty "3 knob" AM rigs showed up for $49. In 1975, you couldn't even get a 6 channel radio for that price. Of course, by the mid 80's, Japan was pretty much out of the picture, and radios were being made in all sorts of other Pacific Rim countries, which pretty much accounted for the price drop.

[Trapper_267]

Jan 29, 2017 1:41:29 GMT -5 kc said:

It looks like there are 3 variants of this radio, 1. M#674 , 2. M#674a , 3. M#674b

Also 2 variants of the VFO , 1. M#675 , 2. M#675a

I ordered the SAMS #70 for the radio variants 674 / 674a

I also ordered the SAMS #64 for both variants of the VFO 675 / 675a

Both were on E-bay, very reasonable,They should be here next week, And I would be glad to Scan and Share with anyone interested.

Any info regarding this Radio and VFO would still be greatly appreciated.

Thanks again!!   73's

Hey KC.
Did you ever get your Sam's Book's?

[sean]

Hello all, I also recently purchased a hy- gain hy-range V 674a and hy-range VI 675 at a resale shop here in Oklahoma. I am trying to find out what the "simple" modification is that allows transmit thru the 675. My 674a must be the version that had the pigtail added after purchase. Any and all info will be a huge help. I have noticed there seems to be a lot more available info on the 674b. I also purchased a B at the same shop, it is not in as good of condition as the A but is working. I am new to the blog and look forward to learning from the veterans of the hobby.

[Sandbagger]

May 5, 2017 8:47:56 GMT -5 sean said:

Hello all, I also recently purchased a hy- gain hy-range V 674a and hy-range VI 675 at a resale shop here in Oklahoma. I am trying to find out what the "simple" modification is that allows transmit thru the 675. My 674a must be the version that had the pigtail added after purchase. Any and all info will be a huge help. I have noticed there seems to be a lot more available info on the 674b. I also purchased a B at the same shop, it is not in as good of condition as the A but is working. I am new to the blog and look forward to learning from the veterans of the hobby.

I've never had the pleasure of actually having the Hy-Gain 674/675 combo in my hot little hands. But the local lore in the tech circles back in the 70's was that it was a simple snip of one wire that enabled VFO controlled transmit.

[Trapper_267]

Howdy Sean.
Nice find. You come across any more i want first dibb's. lol

I take it your 674A Didn't have the VFO plug in the back cover if it has the pigtail? Interesting thing there.

Did you get any owner's manual's with your 674 and 675?

I know for a fact that my 674B has the pigtail and my 675 is a A model and i can transmit AM through the 675A. But i can't transmit through the 675A on SSB.

I always thought and herd that i needed a 674A to do SSB through the 675A. This may be a lie though. Other's reading this post may be able to help.

I'll look for my owner's manual for the 675A, I remember the wiring diagram's that are in it and how to connect the 675A to other Hy-Range radio's.

I also have the Sam's book's on the 674A, 674B and the 675A.

Chat later, Trapp

[buzzsaw]

Good evening from north central Oklahoma. I really appreciate the offered help from my addition to the blog. First off, after getting the 674a and 675 hooked together properly I found that both are transmitting on AM and SSB.
No Mr.Trapper I did not receive owner manuals and the only source I have found is from a company in Canada. They are $19 each. The address is justradios.com. I have not yet ordered hoping I might find elsewhere. I do need them, this is the first radio with ant.adjustments and calibrator that I have operated.
The pigtail comes out between the rear plate and the case, at the top, on the 674a. I tried to add a picture of both A and 675 to my reply but could not get that done. Another interesting thing is the 674a was made in June 1975, date stamped in plate, the 674b was made in September same year with date written on plate. I also noticed quite a difference in the boards and the 674b is a bit smaller overall.
Again, thanks for the replies to my addition to the blog. Learning as I go along.
Happy Mother's Day to all.
Sean aka Buzzsaw out

[Trapper_267]

Check your pm's Buzzsaw

[Trapper_267]

ust picked this Hy-gain 5 Puerto Rico up today. Notice the chrome color face plate and the PA is on the Squelch control.
Way different than the picture i posted above of Fred Storm's collection

[Trapper_267]

Then you have this Hy-Gain 5 with A to D band's in it.

                                                                                                                                                                                                                                                          
Then here's a Hy-gain 5 with 40 Channel's

[Trapper_267]

        Here's the latest score. No book or pigtail, But i have found the 9 pin chassis socket's.

Now to find my book and wire up the socket and mount it on the back like a 674A.
Cheer's, Trapp

[TheStonerGuy]

Jan 29, 2017 16:13:56 GMT -5 Sandbagger said:

Jan 29, 2017 9:04:34 GMT -5 kc said:

So far these are  the most details I can find out about these radio's , I can't wait to get the SAM's I ordered !!  This will be a fun project. 73    kc

Credit to: CB DAZE: October 2009 A continuation of Woody's 'Nuff Said column from the CBGAZETTE website

Hello Woody,
I thought you might want to know that some of the information on your Hy-Gain V review page at www.cbgazette.com/rev_hygainv.html is not correct. The 674A that you have photos of on that page is definitely NOT a stock configuration - the lighted toggle switches are a modification added by someone. The 674 and 674A had the same push buttons as the 674B. The 674 had the VFO socket on the back, as pictured; the 674A was the same internally as the 674, but the VFO socket and wiring was left out. There was either an empty hole or a blank panel, depending on the vintage of the 674A. A wiring harness and instructions was included with later model 675A VFOs so they could be added to the 674A (and other 6xxA models, excepting of course 623A)that did not include the socket.
Another way to tell the difference between the 674/A and the 674B is the 674/A models used a 4-pin mic jack; the 674B a 5-pin DIN. There is also an access hole on the back of the 674/A models for adjustment of the "Load" capacitor. This hole is absent on the 674B. The speaker grille is also in a different location, being on the side of the 674/A and the bottom of the 674B. There are other subtle differences in the outer case design, but these are the big ones. From the pic on your page, the model shown is quite definitely a 674, as is shown clearly by the model tag. The 674A would be labeled as such, and did not have the VFO socket screwed to the chassis.
I live in Lincoln, Nebraska, and work in the former Hy-Gain plant. I've seen many of the various flavors of 674 over the years (although I did not work at Hy-Gain in those days). You are correct in that it is the easiest 10-Meter conversion ever - I have a 674A/675A that I put on 10meters many years ago, and currently another one on the bench for a friend undergoing the same conversion. A point of trivia, the 675A VFO can be connected to the 674B - if you know what you are doing. It requires adding an 11.272 crystal in the carrier oscillator circuit, some re-wiring of the synthesizer switching around the mode switch, and the 674B MUST have a black-label crystal filter. The later versions used a silver labeled crystal filter that was broader (compromise for AM operation) and does not work as well. I did one of these years ago, and it's probably still floating around here somewhere. It may be the only one in the country, AFAIK. These days, it's not worth the effort, of course. But it can be done. Jim.

Again Thank-You Woody and Jim !

  I suppose I'll have to correct that info one day    Tnx for letting me know. I have couple things to add: The instruction booklet that came with the 675 VFO had directions on how to wire it directly into the Hy-Gain CB's (all models of that era, AM or SSB), as only one model 674 actually had the socket on the back (at least from what I've run across). Also, TAB Publications had a series of books similar to CB-SAMS. Volume 1 covers the 670, 671, 672, 673, 674, 675, and 623 models w/schematics, board layouts, etc. A smaller sized book, but useful nonetheless. The VFO is always "on" no matter if the radio is in transmit or receive. During Xmit the supply voltage is returned to the radio via Pin 5 of the VFO socket which lets it know to use to the internal synthesizer.  Woody

[Sandbagger]

Jun 3, 2019 18:04:40 GMT -5 TheStonerGuy said:

Jan 29, 2017 16:13:56 GMT -5 Sandbagger said:

  I suppose I'll have to correct that info one day    Tnx for letting me know. I have couple things to add: The instruction booklet that came with the 675 VFO had directions on how to wire it directly into the Hy-Gain CB's (all models of that era, AM or SSB), as only one model 674 actually had the socket on the back (at least from what I've run across). Also, TAB Publications had a series of books similar to CB-SAMS. Volume 1 covers the 670, 671, 672, 673, 674, 675, and 623 models w/schematics, board layouts, etc. A smaller sized book, but useful nonetheless. The VFO is always "on" no matter if the radio is in transmit or receive. During Xmit the supply voltage is returned to the radio via Pin 5 of the VFO socket which lets it know to use to the internal synthesizer.  Woody

Woody, is that you? Long time no see. How have you been?

[TheStonerGuy]

Jun 3, 2019 18:18:07 GMT -5 Sandbagger said:

Jun 3, 2019 18:04:40 GMT -5 TheStonerGuy said:

Woody, is that you? Long time no see. How have you been?

Yep, me. You're right about 'long time' (what's it been, 9 or 10 years now?). Like most folks, I've had up's and down's. Nice to see U R still kick'n too! I just took the Hy-Gain pair (674/675) out of the storage closet the other day to dust them off, and power up for a bit (nothing popped ). I figured I'd do a Google to see if anyone was still messing with them and came across this thread.

[oldhygain]

Jun 3, 2019 18:04:40 GMT -5 TheStonerGuy said:

Jan 29, 2017 16:13:56 GMT -5 Sandbagger said:

  I suppose I'll have to correct that info one day    Tnx for letting me know. I have couple things to add: The instruction booklet that came with the 675 VFO had directions on how to wire it directly into the Hy-Gain CB's (all models of that era, AM or SSB), as only one model 674 actually had the socket on the back (at least from what I've run across). Also, TAB Publications had a series of books similar to CB-SAMS. Volume 1 covers the 670, 671, 672, 673, 674, 675, and 623 models w/schematics, board layouts, etc. A smaller sized book, but useful nonetheless. The VFO is always "on" no matter if the radio is in transmit or receive. During Xmit the supply voltage is returned to the radio via Pin 5 of the VFO socket which lets it know to use to the internal synthesizer.  Woody

I have my Hygain 674B, serial 268. Yes there was a modification for 674B to make it have variable VFO for transmit as well. My old notes said to just remove green wire off fine tune control and move to brown wire connection.  This worked back in the 80s for B model only, I know on the early models for sure.

[Trapper_267]

May 18, 2020 22:25:39 GMT -5 oldhygain said:

Jun 3, 2019 18:04:40 GMT -5 TheStonerGuy said:

I have my Hygain 674B, serial 268. Yes there was a modification for 674B to make it have variable VFO for transmit as well. My old notes said to just remove green wire off fine tune control and move to brown wire connection.  This worked back in the 80s for B model only, I know on the early models for sure.

This is interesting, oldhygain. I know in the day my 674B with the 675A did transmit AM through the VFO. But if i remember it couldn't do SSB.

[Trapper_267]

Here's a update on the 675 VFO to be able to transmit using the vfo. Take the 9 pin connector apart that plug's into the radio off the vfo. Unsolder or just cut the orange wire to pin #3 and that's it.
Now you can transmit through the VFO.
Now here's something else i just figured out. Using a freq counter, Set your AM transmit through the vfo to let's say 27.38500, Now inject a tone and switch the Hygain 5 to USB, You will see now the frequency is now at 27.3861, So there's your upper SSB offset. Now inject the tone again and switch to LSB. Note that your transmit freq. is now 27.3867. So for some reason it doesn't reconfugure the LSB Lower offset.  
I tried this on different modles of the 674/A and other 675's and apperently it's all the same. Granted we were not suspost to Transmit through these slider's anyway.
So just a little FYI, IF you go to LSB, You will have to set your VFO using a tone to accuire your LSB offset, A good place to set it would be 1.5 HZ lower than the frequency or channel your using atm.
Enjoy and be safe, Trapp