Johnson VFO 122/Heathkit DX-60A help

[VA3AEX]

With my HG-10 VFO crapping out (haven't sorted that out), I'm looking to pair up a Johnson VFO 122 with a Heathkit DX-60A, and I'm stymied by how to key the VFO.

For the Johnson manual shows pin outs as follows:
1,2  Ground
3     250V-300V
7     6.3V
8     Keying circuit

DX-60A shows pin out:
1     Ground
2     6.3V
4     300V
5,6   110V relay circuit
8      Bias (voltage?)

I would like the VFO keyed by the DX-60A, rather than run continuously, and don't want to modify the DX-60A as this is only a short term solution (although we know that sometimes these become permanent solutions!).  I'm thinking that I could use the extra pole on my antenna relay to short out the VFO jack when the transmitter is switched to transmit.  Ideas? other suggestions? 

73 Alex

[w4bfs]

hi Alex .... from your nicely detailed interface info it seems that Heath sent keyed 110 Vac to the Heath vfo to key a small relay to activate the vfo ....you could do the same to your efJ 122 from what I see here

this brings up a larger point .... doing this generates yet another non standard interface .... please ink some info on a paper tag and hang on the octal plug to alert someone this is a custom interface

[WQ9E]

Alex,

As I recall, the DX-60 uses grid block keying.  If my memory is correct then the following applies:  There is a section in the back of the Johnson VFO-122 manual which describes modifying the earlier Johnson rigs to this keying system and following this is a description of a few simple modifications you need to make to the VFO itself.  Then it will work fine with any rig using grid block keying.

The alternative, if you are not using full break-in, is to use an extra set of contacts on your T/R relay to activate the VFO (through its keying jack) only during transmit.  This is the least chirpy way to key the VFO-122.  Just put a regular 1/4" phone plug into the key jack on the VFO and connect this to a set of normally open contacts that are closed when in transmit.  This is how I have the VFO-122 set up with my Viking 1 and 2 since I don't operate full break-in with them.

[KD3CN]

Hi Alex,
I'm not sure if this will be a problem for you or not (never owned a DX-60).  But if you plan to use the VFO-122 on 80m, I believe it's output is on 160m.  Also I believe the HG-10's output is on 80m.  If the DX-60 doesn't multiply the input for 80m (straight-thru), it won't be happy about the 160m signal from the VFO-122.
I had this problem with a VF-1 and Eico-720.
73, Karl

[VA3AEX]

Thanks to all for the suggestions!

Rodger, I don't need full break in keying so I'll try using the spare set of contacts on the ant relay to activate the VFO -- simple/fast/easy!

Karl, not sure if the DX60 will multiply the 160M VFO output or not on 80M.  As I do want to use it there, I'll have to dig through the manual.

Hope to get to it this weekend, and I'll post an update.

73  Alex